Vaginal Progesterone Administration Research Articles

Comparison of vaginal versus intramuscular progesterone in programmed cycles for frozen-thawed blastocyst transfer in patients with endometriosis

BackgroundPrevious studies have shown that due to the presence of endometrium progesterone resistance in patients with endometriosis, it is considered that higher levels of progesterone may be required to achieve live birth during programmed frozen-thawed embryo transfer (FET) cycles. Currently, the optimal progesterone support in FET cycles remains a contentious issue, and it mainly focused on the general infertile population, without specific attention to infertile patients with endometriosis. This study aimed to compare the pregnancy outcomes between vaginal or intramuscular progesterone administration in patients with endometriosis, and to determine whether the stage of endometriosis moderates the differences.MethodsThis retrospective cohort study included patients with endometriosis who underwent their first single frozen-thawed blastocyst transfer in a programmed cycle from January 2018 to April 2024 at a university-affiliated reproductive medical center. According to the routes of luteal support, patients were divided into vaginal progesterone and intramuscular progesterone groups. Analyses were conducted using multivariate regression models and subgroup analysis. Interaction tests were employed to determine whether the revised American Society for Reproductive Medicine (r-ASRM) stages of endometriosis moderated the differences between the routes of progesterone administration and pregnancy outcomes.ResultsA total of 825 programmed frozen-thawed blastocyst transfer cycles were included in the analysis, with 362 cases using vaginal progesterone and 463 cases using intramuscular progesterone. In the overall cohort, clinical pregnancy rate of the vaginal progesterone group was 49.17%, comparable to 44.06% of the intramuscular progesterone group (aOR 0.82, 95% CI 0.61–1.11). Similarly, there was no statistically significant difference in miscarriage rates between the two groups (16.85% versus 24.51%; aOR 1.57, 95% CI 0.90–2.75). In the subgroup analysis in patients classified as r-ASRM stages I-II, clinical pregnancy rate of vaginal progesterone group was significantly higher than that of intramuscular group (aOR 0.74, 95% CI 0.58–0.93, P = 0.011). Whereas, in patients with stages III-IV, no significant differences in pregnancy outcomes between the two groups were detected. Interaction tests between the routes of progesterone administration and r-ASRM stages were significant (P = 0.036).ConclusionsIn the first single frozen-thawed blastocyst transfer cycles for endometriosis patients with r-ASRM stages I-II, vaginal progesterone favours a higher clinical pregnancy rate compared to the intramuscular progesterone.

Comparing the outcomes of in-vitro fertilization in patients receiving vaginal, subcutaneous, and intramuscular progesterone for luteal phase support: a three-armed randomized controlled trial

BackgroundThe optimal approach to luteal-phase support in infertility treatment remains a subject of debate. This study was conducted to investigate the clinical outcomes, side effects, and patient satisfaction associated with vaginal, subcutaneous, and intramuscular progesterone administration in infertile women undergoing Frozen Embryo Transfer (FET).MethodsThis three-armed randomized clinical trial assigned infertile patients eligible for FET to three progesterone treatment groups: vaginal suppositories (400 mg twice daily; n = 100), subcutaneous injections (25 mg daily; n = 102), and intramuscular injections (50 mg daily; n = 108). The primary outcomes were chemical and clinical pregnancy rates per embryo transfer cycle, with chemical pregnancy defined as beta-human chorionic gonadotropin levels > 50 IU/mL two weeks post-transfer and clinical pregnancy confirmed by ultrasound four weeks later. Exploratory outcomes included progesterone-related adverse effects and participant satisfaction, assessed via a Likert-scale survey 12 weeks post-transfer. Statistical analyses included Chi-square tests for categorical data, one-way analysis of variances, and Kruskal–Wallis tests for continuous data.ResultsThe intramuscular progesterone group had significantly higher chemical pregnancy rates compared to the vaginal and subcutaneous groups (41.7% vs. 26.0% and 27.5%, respectively; p = 0.026). Although the clinical pregnancy rate was also higher in the intramuscular group (32.4%) compared to the vaginal (23.0%) and subcutaneous groups (21.6%), this difference was not statistically significant (p = 0.148). Additionally, patient satisfaction was greater with vaginal and subcutaneous applications than with intramuscular injections (p < 0.001), likely due to a significantly higher incidence of side effects, such as pain and edema at the injection site, in the intramuscular group (p < 0.001).ConclusionsWe found that intramuscular progesterone resulted in higher chemical pregnancy rates than vaginal or subcutaneous routes, but this did not translate into higher clinical pregnancy rates. Despite its effectiveness, intramuscular administration was associated with more adverse effects and lower patient satisfaction. Future research should explore optimizing progesterone regimens to balance efficacy and patient comfort.Trial registrationThe trial protocol was registered on December 6, 2020, in the Iranian Registry of Clinical Trials (IRCT), a primary registry in the World Health Organization (WHO) Registry Network, under the registration number IRCT20141217020351N12.

O-001 Human Reproduction Keynote lecture: Progesterone for pregnant people with threatened miscarriage

Abstract Threatened miscarriage, characterized by vaginal bleeding in early pregnancy, affects approximately 25% of all clinical pregnancies. Progesterone supplementation, typically administered vaginally, is a common clinical practice aimed at preventing miscarriage in cases of threatened miscarriage. However, the evidence regarding the effectiveness of this intervention is conflicting and subject to varying interpretations. In a randomized controlled trial conducted in Queensland, Australia, we evaluated the efficacy of nightly 400 mg vaginal progesterone administration, initiated at the onset of bleeding and continued until 12 weeks gestation, in increasing live birth rates among women experiencing threatened miscarriage. Our study did not find evidence supporting a treatment effect of vaginal progesterone in enhancing live birth rates, nor did we find evidence that progesterone improves live birth rates in women with a history of two or more previous miscarriages. We conclude that routine use of progesterone for threatened miscarriage cannot be recommended. However, the potential therapeutic benefit of progesterone in women with threatened miscarriage following recurrent pregnancy losses warrants further investigation through dedicated clinical trials in this population.

P-297 Intensive luteal phase support regimens for endometriosis and adenomyosis patients in hormone replacement therapy frozen embryo transfer cycles – subcutaneous or intramuscular progesterone treatment?

Abstract Study question Does subcutaneous (SC) progesterone treatment provide progesterone levels comparable to intramuscular (IM) progesterone when using a cut-off level of 118nmol/l(37.1ng/ml) during intensive luteal phase support? Summary answer As part of an intensive luteal phase support regimen SC progesterone provides higher P4 levels compared to the use of IM progesterone. What is known already Low serum progesterone (P4) levels in HRT-FET cycles negatively impact reproductive outcomes. This effect is particularly pronounced in patients with endometriosis and adenomyosis, due to reduced progesterone actions and progesterone resistance at the receptor level. Therefore, higher serum P4 levels are required to maintain an optimal reproductive outcome during HRT-FET. A P4 cut-off of 118nmol/l (37.1ng/ml) or above has been suggested, a level four times higher than that of the non-endometriosis patient. To achieve high P4 levels, intensive luteal phase support (LPS) regimen has been suggested. This includes vaginal progesterone administration and additional treatment via IM, SC or rectal administration. Study design, size, duration This cohort study includes 380 HRT-FET cycles in endometriosis/adenomyosis patients. Patients were treated from January 2016 until August 2019 with one type of intensive LPS regimen (n = 262) and from January 2000 to January 2023 with two different LPS regimens depending on whether serum P4 levels were lower or higher than 118nmol/l on the day of blastocyst transfer (BT) (n = 118). P4 was measured in a standardised manner. Participants/materials, setting, methods Patients received treatment in a public university affiliated fertility clinic. Endometrial priming involved the use of estradiol followed by vaginal progesterone. From the fourth day of progesterone, one of the following intensive LPS regimens were added: A) 50mg IM progesterone, B) 25mg SC progesterone BD, or C) 25mg SC progesterone BD plus 400mg rectal rescue progesterone BD if P4&amp;lt;118nmol/l. Blastocyst transfer (BT) and P4 measurement were performed on the sixth day of progesterone administration. Main results and the role of chance The overall pregnancy rate, live birth rate (LBR) and total pregnancy loss rates for the whole cohort were 63%, 41% and 36%, respectively. For the three groups A, B and C the mean serum P4 levels on the day of BT were 103.1 ±44.4nmol/l, 170.5 ±62.9nmol/l and 90.1 ±21.5nmol/l. In Group A (IM) 67% of patients (176/262) had P4 levels &amp;lt;118 nmol/l whereas only 36% (43/118; p &amp;lt; 0.001) had P4 &amp;lt;118 nmol/l in the groups of patients treated with SC progesterone (Group B and C). The unadjusted LBR was not significantly different between groups, 39%, 39%, 51%, (p = 0.32). However, a sub-group analysis showed that comparing patients with serum P4 levels &amp;lt;118nmol/l on the BT day in Group A with patients with P4 levels &amp;lt;118nmol/l in Group C a significantly higher LBR was found if intensive LPS included both SC and rectally administered progesterone compared to IM progesterone, only: 51% (44/86) vs 34% (59/176), p = 0.03. The adjusted odds ratio for live birth was 2.04 (95% CI [1.00, 4.16], p = 0.05) after adjusting for age, vitrification day 5 or 6, blastocyst quality and numbers of blastocysts transferred, if intensive LPS included SC and rectal rescue compared to IM, only in patients with P4 levels &amp;lt;118nmol/l. Limitations, reasons for caution This cohort study was conducted over two different time periods. Single embryo transfer was performed only during the later period. The bio-pharmacological profiles of SC and IM progesterone differ, which can influence serum P4 levels. However, in the present study, all blood samples were collected in a standardised manner. Wider implications of the findings This study is the first to report reproductive outcomes following different intensive LPS regimens in a cohort of endometriosis/adenomyosis patients. To increase reproductive outcomes, individualisation of the HRT-FET cycle may be beneficial and, importantly, rectal progesterone administration can be used as a rescue regimen in addition to SC progesterone. Trial registration number Due to the retrospective study design no ethical approval was needed.

Rectal versus vaginal progesterone administration for luteal phase support in the hormone replacement therapy frozen embryo transfer (HRT-FET) cycle: protocol for a non-inferiority randomised controlled trial

IntroductionThis study compares rectal administration with vaginal administration of progesterone as luteal phase support in hormone replacement therapy frozen embryo transfer (HRT-FET) cycles. The reason for comparing the two routes...

Does the route of administration matter? Systematic review and meta-analysis of randomized clinical trials between vaginal versus intramuscular progesterone administration in the prevention of preterm birth

Does the route of administration matter? Systematic review and meta-analysis of randomized clinical trials between vaginal versus intramuscular progesterone administration in the prevention of preterm birth

Cervical elastography in predicting spontaneous preterm birth in singleton pregnancy with a short cervix receiving progesterone treatment at 18 to 24 weeks’ gestation

Background A short cervix in the second trimester is known to increase the risk of preterm birth, which can be reduced with the administration of vaginal progesterone. However, some studies have suggested that a significant number of cases still experience preterm birth despite progesterone treatment. Objective This study was aimed to investigate the potential value of transvaginal cervical elasticity measured by E-Cervix as a predictor for spontaneous preterm birth (sPTB) in singleton pregnancies receiving progesterone treatment for a short cervix (CL ≤ 2.5 cm) diagnosed at 18 to 24 weeks’ gestation. Study design This prospective study was conducted at a single center premature high-risk clinic from January 2020 to July 2022. Singleton pregnancies with a short cervix at 18 to 24 weeks’ gestation were enrolled. Cervical elastography using E-Cervix was performed, and maternal and neonatal demographic characteristics, cervical length (CL), elasticity contrast index (ECI), cervical hardness ratio, mean internal os strain (IOS), and mean external os strain (EOS) were compared before and after progesterone treatment in sPTB and term birth groups. Multivariate logistic regression was used to analyze the association between elasticity parameters and spontaneous preterm birth. The screening performance of CL and optimal cervical elasticity parameters in predicting sPTB was evaluated using receiver-operating characteristic (ROC) curve analysis. Results A total of 228 singleton pregnant women were included in the study, among which 26 (11.4%) had sPTB. There were no significant differences in maternal characteristics and gestational age at enrollment between women with and without sPTB. At the start of progesterone treatment, there were no significant differences in cervical elasticity parameters between the two groups. After two weeks of progesterone treatment, women who had sPTB showed significantly higher levels of ECI, IOS, EOS (p = 0.0108, 0.0001, 0.016), and lower hardness ratio (p = 0.011) compared to those who had a full-term birth. Cervical length did not show significant differences between the two groups, regardless of whether progesterone treatment was administered before or after. Among the post-treatment cervical elasticity parameters, IOS and EOS were associated with a 3.38-fold and 2.29-fold increase in the risk of sPTB before 37 weeks (p = 0.032, 0.047, respectively). The AUROC of the combined model including CL, IOS, and EOS (0.761, 95% CI0.589–0.833) was significantly higher than the AUROC of CL alone (0.618, 95% CI 0.359–0.876). At a fixed false-positive of 13%, the addition of IOS and EOS in the CL model increased sensitivity from 34.6% to 57.6%, PPV from 25.7% to 36.5%, and NPV from 91.1% to 94.1%. Conclusion When assessing the risk of sPTB in singleton pregnancies with a short cervix receiving progesterone therapy, relying solely on cervical length is insufficient. It is crucial to also evaluate cervical stiffness, particularly the strain of the internal and external os, using cervical elastography.

Individualized luteal phase support in frozen-thawed embryo transfer after intramuscular progesterone administration might rectify live birth rate.

The serum P concentrations are suggested to have an impact on pregnancy outcome. However there is no consensus about the optimal progesterone cut-off during the luteal phase. Few studies evaluated the effectiveness of a "rescue protocol" for low serum P concentrations and most of these studies used vaginal progesterone administration. There is paucity of data on the effectiveness of rescue protocol using intramuscular progesterone (IM-P) in frozen-thawed embryo transfer (FET). This study is a retrospective cohort study included 637 single or double blastocyst FETs with artificially prepared endometrium receiving 100 mg IM progesterone (P) after incremental estrogen treatment. Serum P concentrations were evaluated using blood samples obtained 117-119 hours after the first IM-P administration and 21 ± 2 hours after the last IM-P administration. Patients with serum P concentrations <20.6 ng/ml on the ET day were administrated 400 mg vaginal progesterone for rescue. Demographic and cycle characteristics were similar between patients receiving rescue vaginal P (embryo transfer (ET)-day P concentration < 20.6 ng/ml) and patients who did not need rescue vaginal P (ET-day P concentration ≥ 20.6 ng/ml). Clinical pregnancy, miscarriage, and live birth rates were similar between two groups: 52.9%(45/85) vs 59.6%(326/552), p=0.287; 11.1%(5/45) vs 14.1%(46/326), p=0.583; and 47.1%(40/85) vs 50.7%(280/552), p=0.526, respectively. Logistic regression analysis revealed that the female age (p = 0.008, OR=0.942, 95% CI = 0.902-0.984) and embryo quality (ref: good quality for moderate: p=0.02, OR=0.469, 95% CI =0.269-0.760; for poor: p=0.013, OR= 0.269, 95% CI = 0.092-0.757) were independent variables for live birth. Following rescue protocol implementation, ET-day P concentration was not a significant predictor of live birth. Rescue vaginal P administration for low ET day serum P concentrations following IM-P yields comparable live birth rates.

Comparison of Individualized Rescue Luteal Phase Support Strategies with Vaginal and Combined Vaginal & Subcutaneous Progesterone Administration in Artificial Frozen-Thawed Blastocyst Embryo Transfer Cycles Based on Serum Progesterone levels.

Hormone replacement therapy (HRT) frozen embryo transfer (FET) cycles are common in assisted reproductive techniques. As the corpus luteum is absent in these cycles, luteal phase support is provided by administering progesterone (P4) through transvaginal, parenteral, or oral routes. Low serum levels of P4 (below 9-10 ng/mL) on the day before embryo transfer (ET) have been associated with unfavorable cycle outcomes. The aim of this study is to investigate whether individualizing luteal support through rescue protocols in patients with low serum P4 levels improves pregnancy outcomes in HRT-FET cycles. This retrospective, single-center cohort analysis includes 1257 cycles involving 942 patients undergoing HRT-FET. Starting in 2019, we have assessed P4 levels before ET day and adjusted MVP doses when P4 levels were <10 ng/mL. In 2021, subcutaneous (SC) P4 was routinely added alongside MVP, with SC doses increased if P4 levels were <10 ng/mL. In this study, Groups 1 and 2 received MVP for luteal support, while Groups 3 and 4 received additional SC progesterone. For patients with P levels below the cut-off level (10 ng/mL) in Groups 2 and 4, the P dose was doubled through a rescue protocol. In the MVP and MVP plus SC groups, 15.8% and 8.9% of the cycles had P4 levels <10 ng/mL, respectively. Ongoing pregnancy rates (OPR) and clinical pregnancy rates (CPR) did not differ between study groups. Regression analysis with a mixed model revealed that age, endometrial thickness, and estradiol levels were confounding factors as well as independent predictors of ongoing pregnancy rates (p<0.05). Pairwise regression analysis revealed no significant differences in pregnancy rates between the groups (p>0.05). Individualizing luteal phase support based on serum P4 levels on the day of ET in FET cycles with HRT may enhance pregnancy outcomes by either doubling the vaginal dose or increasing the SC dose during MVP plus SC administration. The implemented rescue protocol allowed patients with low progesterone levels to achieve pregnancy outcomes similar to those with higher progesterone levels.

Circadian serum progesterone variations on the day of frozen embryo transfer in artificially prepared cycles

What is the intra-day variation of serum progesterone related to vaginal progesterone administration on the day of frozen embryo transfer (FET) in an artificial cycle? A prospective cohort study was conducted including 22 patients undergoing a single blastocyst artificial cycle (AC)-FET from August to December 2022. Endometrial preparation was achieved by administering oestradiol valerate (2mg three times daily) and consecutively micronized vaginal progesterone (MVP; 400mg twice daily). A blastocyst FET was performed on the 6th day of MVP administration. Serum progesterone concentrations were measured on the day of transfer at 08:00, 12:00, 16:00 and 20:00 hours. The first and last blood samples were collected just before MVP was administered. The mean age and body mass index of the study population were 33.95±3.98 years and 23.10±1.95kg/m2. The mean P-values at 08:00, 12:00, 16:00 and 20:00 hours were 11.72±4.99, 13.59±6.33, 10.23±3.81 and 9.28±3.09ng/ml, respectively. A significant decline, of 2.41ng/ml (95% confidence interval 0.81-4.00), was found between the first and last progesterone measurements. A statistically significant intra-day variation of serum progesterone concentrations on the day of FET in artificially prepared cycles was observed. This highlights the importance of a standardized procedure for the timing of progesterone measurement on the day of AC-FET. Of note, the study results are applicable only to women using MVP for luteal phase support; therefore it is necessary to confirm its validity in comparison with the different existing administration routes of progesterone.

Rectal progesterone administration secures a high ongoing pregnancy rate in a personalized Hormone Replacement Therapy Frozen Embryo Transfer (HRT-FET) protocol: a prospective interventional study.

Can supplementation with rectal administration of progesterone secure high ongoing pregnancy rates (OPRs) in patients with low serum progesterone (P4) on the day of blastocyst transfer (ET)? Rectally administered progesterone commencing on the ET day secures high OPRs in patients with serum P4 levels below 35 nmol/l (11 ng/ml). Low serum P4 levels at peri-implantation in Hormone Replacement Therapy Frozen Embryo Transfer (HRT-FET) cycles impact reproductive outcomes negatively. However, studies have shown that patients with low P4 after a standard vaginal progesterone treatment can obtain live birth rates (LBRs) comparable to patients with optimal P4 levels if they receive additionalsubcutaneous progesterone, starting around the day of blastocyst transfer. In contrast, increasing vaginal progesterone supplementation in low serum P4 patients does not increase LBR. Another route of administration rarely used in ART is the rectal route, despite the fact that progesterone is well absorbed and serum P4 levels reach a maximum level after ∼2 h. This prospective interventional study included a cohort of 488 HRT-FET cycles, in which a total of 374 patients had serum P4 levels ≥35 nmol/l (11 ng/ml) at ET, and 114 patients had serum P4 levels <35 nmol/l (11 ng/ml). The study was conducted from January 2020 to November 2022. Patients underwent HRT-FET in a public Fertility Clinic, and endometrial preparation included oral oestradiol (6 mg/24 h), followed by vaginal micronized progesterone, 400 mg/12 h. Blastocyst transfer and P4 measurements were performed on the sixth day of progesterone administration. In patients with serum P4 <35 nmol/l (11 ng/ml), 'rescue' was performed by rectal administration of progesterone (400 mg/12 h) starting that same day. In pregnant patients, rectal administration continued until Week 8 of gestation, and oestradiol and vaginal progesterone treatment continued until Week 10 of gestation. Among 488 HRT-FET single blastocyst transfers, the mean age of the patients at oocyte retrieval (OR) was 30.9 ± 4.6 years and the mean BMI at ET 25.1 ± 3.5 kg/m2. The mean serum P4 level after vaginal progesterone administration on the day of ET was 48.9 ± 21.0 nmol/l (15.4 ± 6.6 ng/ml), and a total of 23% (114/488) of the patients had a serum P4 level lower than 35 nmol/l (11 ng/ml). The overall, positive hCG rate, clinical pregnancy rate, OPR week 12, and total pregnancy loss rate were 66% (320/488), 54% (265/488), 45% (221/488), and 31% (99/320), respectively. There was no significant difference in either OPR week 12 or total pregnancy loss rate between patients with P4 ≥35 nmol/l (11 ng/ml) and patients with P4 <35 nmol/l, who received rescue in terms of rectally administered progesterone, 45% versus 46%, P = 0.77 and 30% versus 34%, P = 0.53, respectively. OPR did not differ whether patients had initially low P4 and rectal rescue or were above the P4 cut-off. Logistic regression analysis showed that only age at OR and blastocyst scoring correlated with OPR week 12, independently of other factors like BMI and vitrification day of blastocysts (Day 5 or 6). In this study, vaginal micronized progesterone pessaries, a solid pessary with progesterone suspended in vegetable hard fat, were used vaginally as well as rectally. It is unknown whether other vaginal progesterone products, such as capsules, gel, or tablet, could be used rectally with the same rescue effect. A substantial part of HRT-FET patients receiving vaginal progesterone treatment has lowserum P4. Adding rectally administered progesterone in these patients increases the reproductive outcome. Importantly, rectal progesterone administration is considered convenient, and progesterone pessaries are easy to administer rectally and of low cost. Gedeon Richter Nordic supported the study with an unrestricted grant as well as study medication. B.A. has received unrestricted grant from Gedeon Richter Nordic and Merck and honoraria for lectures from Gedeon Richter, Merck, IBSA and Marckyrl Pharma. P.H. has received honoraria for lectures from Gedeon Richter, Merck, IBSA and U.S.K. has received grant from Gedeon Richter Nordic, IBSA and Merck for studies outside this work and honoraria for teaching from Merck and Thillotts Pharma AB and conference expenses covered by Merck. The other co-authors have no conflict of interest to declare. EudraCT no.: 2019-001539-29.

P-511 Prolonging the time of vaginal progesterone supplementation does not improve pregnancy outcomes after day 6 blastocyst transfer

Abstract Study question Does the administration of vaginal progesterone for 6 days improve pregnancy outcomes when transferring day 6 blastocysts, as opposed to 5 days of progesterone treatment? Summary answer We observed similar pregnancy outcomes after 5 and 6 days of vaginal progesterone supplementation following day 6 blastocyst transfer in oocyte recipient cycles. What is known already Progesterone administration promotes the final phase of endometrial preparation for embryo transfer. However, the optimal duration of progesterone transformation still remains unknown. The implantation potential of blastocysts formed at different timepoints is also contentious, as blastocysts on day 6 have been linked to poorer clinical outcomes compared to their day 5 counterparts. It is unclear whether this effect stems from an intrinsic impaired implantation capacity of slow-developing blastocysts, or a displaced window of implantation (WOI). It has been hypothesized that 6 days of progesterone administration may improve clinical outcomes after frozen day 6 blastocyst transfer. Study design, size, duration Retrospective cohort study of oocyte recipients undergoing single day 6 blastocyst transfer, between January 2020 and December 2022. This study compared two groups: day 6 blastocysts transferred after 5 days of progesterone administration (n = 284) and day 6 embryo transfers performed after 6 days of progesterone administration (n = 69). Participants/materials, setting, methods Our study included oocyte recipients who underwent a single embryo transfer of a day 6 blastocyst and hormonal replacement treatment for endometrial preparation with vaginal external progesterone administration (800mg/24h) for either 5 or 6 days prior to embryo transfer. Outcomes were analyzed using unpaired t-test or Fisher’s test and logistic regression. Multivariate models were adjusted for oral or transdermal estrogen administration and endometrial thickness on the day of embryo transfer. P-values &amp;lt;0.05 were considered significant. Main results and the role of chance Mean maternal age was 43.5 years, while patients had a mean BMI of 25.1. Mean days of estrogen therapy prior to embryo transfer were 22.4, with 75.3% of patients using transdermal estrogen administration, and achieving a mean endometrial thickness of 9.6 mm on the day of transfer. Mean progesterone levels on the day of transfer were 11.9 ng/ml. Thirty-seven percent of the day 6 blastocysts were of high quality. None of the demographic or cycle characteristics were significantly different between the study groups. When considering outcomes of day 6 blastocyst transfers, we found no significant differences in biochemical (26.33% vs 20.13%, p = 0.343), clinical (22.06% vs 17.46%, p = 0.49) and ongoing (14.64% vs 9.52%, p = 0.41) pregnancy rates between 5 and 6 days of progesterone administration. Our adjusted analysis further corroborated these results. Limitations, reasons for caution The retrospective nature of the study and low number of transfers performed after 6 days of progesterone treatment warrant careful interpretation. This study only evaluated endometrial preparation by vaginal progesterone administration in oocyte recipients and cannot be extrapolated to other routes of progesterone administration or other patient populations. Wider implications of the findings Poorer reproductive outcomes associated with the transfer of day 6 blastocysts appear to be related to a reduced implantation capacity of slow-developing embryos rather than a displaced WOI due to rising progesterone. WOI appears wider than assumed, as prolonged progesterone transformation times had no effect on pregnancy outcomes. Trial registration number Not applicable

P-596 Rectal progesterone administration secures high ongoing pregnancy rate in a personalized Hormone Replacement Therapy Frozen Embryo Transfer (HRT-FET) protocol - a prospective interventional study

Abstract Study question Can supplementation with additional rectal administration of progesterone secure high ongoing pregnancy rates (OPR) in patients with low serum progesterone (P4) at blastocyst transfer (ET)? Summary answer Rectally administered progesterone starting on the blastocyst transfer day secures high OPR in patients with serum P4 levels lower than 35 nmol/l (11ng/ml). What is known already Low serum P4 levels at peri-implantation in HRT-FET cycles impact reproductive outcomes negatively. However, studies have shown that patients with low P4 after a standard vaginal progesterone treatment can obtain live birth rates (LBR) comparable to patients with optimal P4 levels if they receive additional subcutaneous progesterone, starting close to the day of blastocyst transfer. In contrast, increasing vaginal progesterone supplementation in low serum P4 patients does not increase LBR. Another route of administration rarely used in ART is the rectal route, although progesterone is well absorbed and serum P4 levels reach a maximum level after approximately two hours. Study design, size, duration This prospective interventional study included a cohort of 488 patients treated with single blastocyst HRT-FET, in which a total of 374 patients had a serum P4 level ≥35nmol/l (11ng/ml) at ET, and 114 patients had a serum P4 level &amp;lt;35nmol/l (11ng/ml). The study was conducted from January 2020 to November 2022. Participants/materials, setting, methods Patients undergoing HRT-FET in a public Fertility Clinic. Endometrial preparation included oral oestradiol (6mg/24hours), followed by vaginal micronized progesterone, 400mg/12hours. Single blastocyst transfer and P4 measurements were performed on the 6th day of progesterone administration and patients with serum P4 &amp;lt;35nmol/l (11ng/ml) additional rectal administration of progesterone (400mg/12hour) was started the same day. In pregnant patients, vaginal and rectal administration continued until week 8, and oestradiol and vaginal progesterone treatment continued until week 10. Main results and the role of chance Among 488 HRT-FET single blastocyst transfers, the mean age of the patients at oocyte retrieval (OR) was 30.9 ±4.6 years and the mean BMI at ET 25.1 ±3.5 kg/m2. The mean serum P4 level after vaginal progesterone administration on the day of blastocyst transfer was 48.9 ±21.0 nmol/l (15.4 ±6.6ng/ml), and a total of 23% (114/488) of the patients had a serum P4 level lower than 35nmol/l (11ng/ml). The overall, positive hCG rate, clinical pregnancy rate, OPR week 12, and total pregnancy loss rate were 66% (320/488), 54% (265/488), 45% (221/488), and 31% (99/320), respectively. There was no significant difference in neither OPR week 12 nor total pregnancy loss rate between patients with P4 ≥35nmol/l (11ng/ml) and patients with P4 &amp;lt;35nmol/l, who received rescue in terms of rectally administered progesterone, 45% vs. 46%, p = 0.77 and 30% vs. 34%, p = 0.53, respectively. OPR did not depend on whether patients had initially low P4 and rectal rescue or were above the P4 cut-off. Logistic regression analysis showed that only age at OR and blastocyst scoring correlated with OPR week 12, independently of other factors like BMI, and vitrification day of blastocysts (day 5 or 6). Limitations, reasons for caution In this study vaginal progesterone (Cyclogest®), a solid pessary with progesterone suspended in vegetable hard fat, was used vaginally as well as rectally. It is unknown whether other vaginal progesterone products could be used rectally as easily with the same rescue effect. Wider implications of the findings A substantial part of HRT-FET patients receiving vaginal progesterone treatment has low serum P4. Adding rectally administered progesterone in these patients increases the reproductive outcome. Importantly, rectal progesterone administration is considered convenient by the majority of patients; moreover, progesterone pessaries are easy to administer rectally and of low cost. Trial registration number EudraCT no.: 2019-001539-29

P-595 What to expect from “standard vaginal progesterone regimen” in Hormone Replacement Therapy Frozen Embryo Transfer (HRT-FET) – do different products result in different serum levels?

Abstract Study question Do luteal serum progesterone levels (P4) vary in relation to time of blood sampling, the type and dosing of vaginal progesterone products used for HRT-FET? Summary answer Significant differences in luteal serum P4 levels exist between time of blood sampling as well as between different vaginal progesterone products and the administration regimen. What is known already Mid-luteal P4 levels below 9-11 ng/ml have been shown to negatively affect reproductive outcomes in HRT-FET cycles. Formulations of vaginal progesterone products differ as progesterone can be suspended in vegetable hard fat, in a vegetable lipophile liquor, be prepared in an oil-in-water emulsion carrier, or mixed in a tablet. Moreover, dosing regimens vary from one to three times daily, and BMI, age, and parity affect serum P4 levels; importantly, no consensus exists in terms of optimal time point to measure P4 in relation to administration, the specific serum P4 cut-off level to use or the most optimal vaginal progesterone product. Study design, size, duration Cohort study including 488 HRT-FET blastocyst transfers performed from January 2020 to November 2022 in patients undergoing a “standard vaginal progesterone regimen”. Each patient participated only once in the study. To compare the vaginal progesterone product used in the present study, we reviewed the most recent literature, including data from six studies, using three different products in six different regimens; all studies were cohort studies, including between 227 -1150 patients undergoing a “standard” HRT-FET protocol. Participants/materials, setting, methods A total of 488 patients in a public Fertility Clinic underwent HRT-FET, including endometrial preparation with oral oestradiol (6mg/24hours), followed by vaginal micronized progesterone, 400mg/12hours (Cyclogest®). Blood sampling on the blastocyst transfer day was standardised to two to four hours after progesterone administration. In contrast, P4 was measured randomly on the day of pregnancy testing. For comparison a review of the literature from six HRT-FET cohort studies using either Crinone®, Utrogestan® or “PIVET”-pessaries was performed. Main results and the role of chance The mean serum P4 (2-4 hours after administration) on the day of blastocyst transfer in our cohort was 15.4 ±6.6ng/ml. On the day of pregnancy testing (random time points) serum P4 levels were divided into four groups, depending on the time from progesterone administration to blood sampling: &amp;lt;2hours, &amp;gt;2&amp;lt;4hours &amp;gt;4&amp;lt;6hours and &amp;gt;6hours.The mean P4 levels were 14.7 ±6.3ng/ml, 15.6 ±5.8ng/ml, 14.3 ±4.9ng/ml and 12.9 ±6.4, respectively, and a significant difference was seen, between P4 levels measured 2-4 hours and &amp;gt;6 hours after vaginal administration (p = 0.03). As regards the product, the mean P4 levels in this study (Cyclogest®) was significantly different from the reviewed P4 levels of other “standard” HRT-FET cohorts, using three different products (Uterogestan®, Crinone® and the “PIVET-pessary”) 12.1 ±7.0ng/ml (p &amp;lt; 0.001), 7.6 ±3.2ng/ml (p &amp;lt; 0.001) and 29.3 ±20.3ng/ml (p &amp;lt; 0.001), respectively. As regards the dose, a significant difference in P4 levels was seen between dosing regimens in two cohorts when using the same product (Crinone®) 90mg x 3 vs. 90 mg x 2; 11.3 ±4.7ng/ml and 7.6 ±3.2ng/ml, respectively, p &amp;lt; 0.001. Interestingly, when comparing another product (Utrogestan®) used in different dosing regimens, 400mg x 2 vs. 200mg x 3, no difference in P4 levels was seen, 12.1 ±7.0ng/ml and 11.3 ±5.1ng/ml, P = 0.09. Limitations, reasons for caution In HRT-FET serum P4 levels reflect the exogenous administration, only, and P4 fluctuations depend on the route and number of administrations, as well as absorption and metabolization. The reviewed data used for this comparison between different progesterone products and regimens derive from cohorts with different characteristics and blood sampling timings. Wider implications of the findings Luteal serum P4 measurement is important, however, standardization of blood sampling in relation to the latest vaginal progesterone administration is mandatory to obtain correct levels. Clinicians should be aware of the significant differences in P4 levels related to dose and vaginal absorption between different types of vaginal progesterone products. Trial registration number EudraCT no.: 2019-001539-29

P-649 Circadian serum progesterone variations on the day of frozen embryo transfer in artificially prepared cycles

Abstract Study question What is the intra-day variation of serum progesterone related to vaginal progesterone administration on the day of frozen embryo transfer (FET) in an artificial cycle? Summary answer We observed a statistically significant intra-day variation of serum progesterone (P) levels on the day of FET in artificially prepared cycles (AC). What is known already The use of FET cycles has increased enormously. In an attempt to further optimize pregnancy outcomes after FET, recent studies have focused on the importance of correct serum luteal P levels in both natural and AC-FET cycles. Despite the different cut-off values proposed to define low serum P, it is generally accepted that lower serum P values(&amp;lt;8.8 ng/ml) around the day of FET are associated with lower live birth rates and higher miscarriage rates. However, a single luteal serum P measurement can be misleading given the diurnal variation and the impact of patient characteristics such as age, BMI, parity, ethnicity. Study design, size, duration A prospective cohort study was conducted at a tertiary university-based hospital encompassing twenty-two patients undergoing a single blastocyst transfer in an AC from August to December 2022. Sample size calculation was performed using a paired t-test resulting in twenty-two patients required to detect a difference of 15% between the first and the last daily progesterone value with a false-positive rate of 5%(two-sided),a power of 80%,assuming a standard deviation of change in the outcome of 0.250. Participants/materials, setting, methods Patients with a normal BMI,aged between 18 and 40 years old, were included. Endometrial preparation was achieved by administering estradiol valerate(6 mg/day) until an adequate endometrial thickness was reached. Consecutively, micronized vaginal progesterone(MVP, 800 mg/die) was started five days prior to blastocyst transfer. P levels were evaluated on the day of FET at 08:00h, 12:00h, 16:00h, and 20:00h. The first and last blood samples were collected just before the intake of MVP,at 8:00h and 20:00h. Main results and the role of chance Mean age of the study population was 33.95 ± 3.98 years and BMI 23.10 ± 1.95 kg/m2. Basal FSH was 7.84 ± 2.31 IU/L and estradiol concentration at 8:00h on the day of FET was 206.04 ± 93.32 ng/L. Mean P values at 08:00h, 12:00h, 16:00h and 20:00h were 11.72 ± 4.99 µg/L, 13.59 ± 6.33 µg/L, 10.23 ± 3.81 µg/L and 9.28 ± 3.09 µg/L,respectively. Statistically significant differences in P values were observed between measurements performed at 08:00h and 20:00h (p = 0,007), 8:00h and 12:00h(p &amp;lt; 0,001), 12:00h and 16:00h (p &amp;lt; 0,001), and 16:00h and 20:00h (p = 0,004). The proportion of patients encountering low P values, defined as P &amp;lt; 8.8 ng/ml, was 27,3% at 8:00h, 13,6% at 12:00h, 40,9% at 16:00h, and 36,4% at 20:00h. Moreover, the difference in patients with normal P values (&amp;gt; 8.8 ng/ml) was statistically significant between samples performed at 8:00h and 12:00h and 12:00h and 16:00h (p = 0.009 and p = 0.01 respectively). No difference was observed in normal P values between 16:00h and 20:00h(p = 0.3) and 8:00h and 20:00h(p = 0,07). Additionally, no association was found either between age and BMI and the first progesterone evaluation of the day, neither between these parameters and the difference in P levels between 8:00h and 20:00h. Limitations, reasons for caution The strict inclusion criteria applied in this study could potentially imply a bias when extrapolating the results to a wider infertile population undergoing AC-FET cycles. A confirmation of the findings in larger prospective studies including a more heterogeneous patient population is recommended. Wider implications of the findings The results of this study highlight the importance of a standardized procedure for the timing of progesterone measurements, partly taken into account the last MVP intake. This is especially important when clinical actions, such as additional P supplementation, are considered when low or high P values are encountered. Trial registration number not applicable

Patient attitudes towards and satisfaction with subcutaneous injection of progesterone versus vaginal administration in assisted reproductive technology treatment

A qualitative study with online and face to face interviews with a total of 19 women undergoing an ART treatment. Only women with at least one previous blastocyst transfer using vaginal progesterone or subcutaneous progesterone could be recruited. All participants were included from either the Fertility Clinic at Copenhagen University Hospital - Herlev and Gentofte or from the Fertility Unit at Aalborg University Hospital. The analysis resulted in four themes: (1) medication, (2) everyday life, (3) bodily experiences and (4) infertility or hope. Most informants highlighted the administration of subcutaneous progesterone only once a day and avoidance of the vaginal discharge as clear advantages. Reasons for preferring the vaginal administration were inconvenience of bringing the subcutaneous medication along and resistance to inject oneself. The findings of this study suggest that the satisfaction with the subcutaneous progesterone is generally positive. However, valuable thoughts have given insights into possible areas, which could be improved. Further, that some women prefer vaginal progesterone. The results show that the women are interested in being included in the decision-making when choosing the administration form of progesterone.

Serum Progesterone Concentration and Ongoing Pregnancy Rate in Frozen-Thawed Embryo Transfers with Intramuscular Plus Vaginal Progesterone Administration for Endometrial Preparation

Background: Insufficient serum progesterone level in the implantation phase may reduce the rate of pregnancy during freeze embryo transfer (FET) cycles. The present study aimed to evaluate the impact of FET day serum progesterone level on pregnancy outcomes in patients receiving intramuscular plus vaginal progesterone administration for endometrial preparation. Methods: Based on serum progesterone level on FET day, patients were divided into four quartiles: first (&lt;25%), second (26–50%), third (51%–75%), and fourth (&gt;75%). There was no significant difference among groups in basal characteristics. Results: No statistically significant difference was seen among groups concerning the mean number of retrieved and mature oocytes, embryos transferred, and endometrial thickness (EnT). The rate of implantation (P=0.5), biochemical (P=0.75), clinical (P=0.54), and ongoing pregnancy (P=0.5) were not associated with serum progesterone level on embryo transfer day. Conclusion: We found that there is no association between serum progesterone level on ET day and pregnancy outcome during FET cycles. It seems that combination therapy using intramuscular and vaginal progesterone, keeps the serum progesterone on ET day high enough that eliminates the need for serum progesterone measurement.

VAGINAL PROGESTERONE IN RISK REDUCTION OF PRETERM BIRTH IN WOMEN WITH SHORT CERVIX IN MID TRIMESTER OF PREGNANCY

Background: Preterm labour is a major health challenge in obstetrics. Many risk factors being identified, the most common one is short cervical length, can be diagnosed by transvaginal ultrasound scan after 13 weeks of pregnancy. Vaginal progesterone is the most bioavailable form of progesterone that have effect on uterine and cervix. Progesterone is found to inhibit the production of proinflammatory cytokines and prostaglandins within the uterus and to inhibit myometrial contractility Aim:To evaluate the efficacy of vaginal progesterone administration for preventing preterm birth and decrease perinatal morbidity and mortality in asymptomatic women with a singleton gestation and a mid-trimester sonographic cervical length (CL) ≤ 25 mm. Materials And Methods:This is a prospective study of asymptomatic women with a singleton pregnancy and a sonographic short cervix (&lt;25mm) at 19 + 0 to 23 + 6 weeks of gestation. Women were allocated randomly to receive vaginal progesterone or placebo daily starting from 19 + 0 to 23 + 6 weeks until 36 + 6 weeks, rupture of membranes or delivery, whichever occurred first. Randomization sequence was stratified by centre and history of a previous preterm birth. The primary endpoint was preterm birth before 33 weeks of gestation. Analysis was by intention to treat. Results:Out of 100 patients for whom study was done, 20 lost to followup and remaining divided into two groups: 40 Singleton pregnant women with CL&lt;25mm between 19 + 0 to 23 + 6 weeks of gestation with no sign and symptoms were given daily vaginal progesterone for up to 36 + 6 weeks, rupture of membranes or delivery, whichever occurred first. The dose is 200 mg once daily and a group of 40 women with cervical length of &lt;25 mm between 19 + 0 to 23 + 6 weeks of pregnancy were given no treatment, Maximum distribution belongs to age of 19-24 years followed by 30-34 years. Most of women in this study have no history of preterm labour. In those who received vaginal progesterone 5 women had history of previous preterm labour and five women in no treatment group. It was found that there was statistically significant reduction in preterm labour in women with short cervix &lt;2.5cm with 200mg vaginal progesterone. Conclusions:This updated systematic review and meta-analysis reaffirms that vaginal progesterone reduces the risk of preterm birth and neonatal morbidity and mortality in women with a singleton gestation and a mid-trimester CL ≤ 25 mm, without any deleterious effects on neurodevelopmental outcome. Clinicians should continue to perform universal transvaginal CL screening at 19 + 0 to 23 + 6 weeks of gestation in women with a singleton gestation and to offer vaginal progesterone to those with a CL ≤ 25 mm.

The role of vaginal progesterone in established pre-term labor: A randomized controlled trial.

Pre-term birth (PTB) is the leading cause of mortality and morbidity in newborn and infants. One of the proposed theories is the withdrawal of progesterone, either actual or functional, to be an antecedent to the onset of labor. The aim of the study is to evaluate the role of vaginal progesterone in delaying delivery following an episode of arrested pre-term labor. This is a pragmatic open-label randomized controlled trial that was conducted in the Department of Obstetrics and Gynecology at All India Institute of Medical Sciences, Jodhpur. Hundred patients with singleton pregnancies presenting with pre-term labor between 24 and 34 weeks of gestation and treated successfully with acute tocolysis for 48 hours and steroids covered were randomized to receive either progesterone 400 mg vaginal suppository or no treatment. The primary outcome was the duration of randomization to delivery interval, which was significantly higher in the study than in the control group (28 days versus 10 days). The secondary outcomes such as gestational age at delivery was also higher in the study group compared to the control group (82% versus 60% delivered after 37 weeks in the study group and control group, respectively). The neo-natal outcomes such as birth weight (2802 grams versus 2324 grams), incidence of respiratory distress syndrome (RDS) (13% versus 26%), and newborn intensive care unit (NICU) admission (17% versus 31%) were lower in the study group, which signifies decreased neo-natal morbidities and mortalities in pre-term labor treated with maintenance tocolysis in the form of vaginal progesterone. Administration of vaginal progesterone (400 mg, daily) following an episode of arrested pre-term labor significantly increased the duration to delivery interval; that is, it reduced the rate of PTB before 37, 32, and 28 weeks of gestation among women. It further reduced the neo-natal morbidities such as RDS and NICU admission and increased the birth weight among infants of women assigned to progesterone treatment.

The role of vaginal progesterone for preterm birth prevention in women with threatened labor and shortened cervix diagnosed after 24 weeks of pregnancy.

To determine whether vaginal progesterone treatment for women with a short cervix, diagnosed after 24 weeks of pregnancy, reduces preterm birth rates. A retrospective cohort study that included women with a singleton pregnancy, threatened preterm labor, and a short cervix measured between 24+0 and 33+6 weeks. Women who received vaginal progesterone were compared with women who did not receive progesterone. The primary outcome was spontaneous preterm birth before 37 weeks of pregnancy. Patients who received vaginal progesterone had a lower rate of preterm delivery at less than 37 weeks of pregnancy (18.2% [22/121] versus 28.9% [73/253]; adjusted hazard ratio 0.50; 95% confidence interval 0.28-0.73, P= 0.001). The diagnosis-to-delivery interval was significantly greater in patients who received progesterone than in those who did not-median time to delivery in weeks: 8.2 (interquartile range [IQR] 6.2-9.8) versus 6.6 (4.8-8.8), (P< 0.001). The frequency of neonatal intensive care unit admission was significantly lower in patients who received progesterone than in those who did not (8.3% [10/121] versus 16.2% [41/253], P= 0.04). The administration of vaginal progesterone to patients with an episode of threatened premature labor and a short cervix presenting after 24 weeks of pregnancy was associated with lower rates of premature births.