High P4 Research Articles

Higher serum progesterone level has no negative impact on live birth rate in frozen embryo transfer

Optimal synchronisation between the endometrium and the embryo is key to the success of frozen embryo transfers (FET). It is achieved by administering different doses of exogenous oestrogen and progesterone (P4). The negative impact of low levels of P4 on FET has been reported, but there is a lack of knowledge about which levels are most appropriate. We aimed to evaluate whether high serum P4 levels measured on FET day affect the probability of having a baby at home. This retrospective cohort study includes 7546 FET cycles performed with hormone replacement therapy (HRT) for artificial endometrial preparation. Patients were divided into three groups according to P level on FET day (ng/mL): P4 < 20(n = 6623), P4 ≥ 20–40 (n = 770) and P > 40 (n = 146). Female age was per group P4 < 20 = 38.7 ± 3.1, P ≥ 20–40 = 39.0 ± 3.0, and P4 > 40 = 38.1 ± 2.9 years old (p = 0.53). The group with the highest progesterone levels found lower ongoing pregnancy rates without statistical significance (56.3 % (P4 < 20) vs 56.8 % (P4 ≥ 20-<40) vs 51.4 % (P4 > 40); p = 0.5). Miscarriage rate was also higher, although not significantly: 16.2 % (P4 < 20) vs 15.0 % (P4 ≥ 20-<40) vs 18.0 % (P4 > 40) (p = 0.6). These findings were explored with an adjusted analysis. A higher, but not significant, odds of miscarriage was observed when P4 > 40 ng/ml, aOR = 1.14 (0.75–1.74) (p = 0.55) whereas no such association was found with P4 ≥ 20–40 ng/ml (aOR = 0.92 (0.74–1.15) (p = 0.46)). The probability of livebirth is similar when the patient was P4 > 40 (aOR = 0.77 (0.51–1.15) (p = 0.20)) than when P4 ≥ 20-<40 (aOR = 0.94 (0.79–1.11) (p = 0.47). In conclusion, women with elevated serum P4 levels on the day of FET after HRT do not find their probability of live birth impaired.

Comparative assessment on the effect of long vis-à-vis short-term progesterone priming on reproductive attributes in silent estrus goats

Silent estrus results in spread-out kidding and extended inter-kidding interval in goats. Progesterone (P4) priming for 12-14 days could be one of the approaches for estrus induction with optimum fertility. The present work was carried to comparatively assess the duration of P4 priming on estrus and fertility in silent estrus goats. Sirohi does (n=18) with a history of anestrus and high basal P4 in paired samples were equally divided into three groups. Does in P-0 d group received 200 IU of equine chorionic gonadotropin by intramuscular route. Does in group second and third were subjected to per-vaginal P4 sponges for 7 (P-7 d) and 14 (P-14 d) days, respectively and were given 200 IU equine chorionic gonadotropin following sponge withdrawal. Estrus was monitored for 72 h at 12 h intervals using teaser buck to record estrus per cent, induction time and duration. Estrus induction was highest in P-14 d (6/6) than P-0 d and P-7 d (4/6 and 5/6), respectively. Estrus induction time was shorter in P-7 d and P-14 d than P-0 d. The estrus duration was shortest in P-14 d group. The conception and pregnancy rate did not differ significantly among the groups, though all the does in P-14 d conceived. The fertility was non-significantly higher in P-14 d (6/6) and P-7 d group (5/5) than P-0 d (3/4). It could be concluded that P4 priming for 7-14 days in silent estrus does results in improved reproductive performances.

Corpus luteum proximity alters molecular signature of the small extracellular vesicles and cumulus cells in the bovine ovarian follicle environment

Progesterone (P4) is predicted to act as a negative regulatory hormone for oocyte maturation events; however, its local effects during follicular development remain poorly understood in bovine. The complex process of oocyte meiosis progression is dependent on cellular communication among follicular cells. Besides, the breakdown of this communication, mainly between cumulus cells (CC) and oocyte, through the retraction of cumulus projections connecting these cells can impact oocyte maturation. In our study, we observed that follicles from the ovary ipsilateral to the corpus luteum (CL) containing high intrafollicular P4 concentrations enhance the abundance of proteins detected in follicular-derived small extracellular vesicles (sEVs) predicted to be involved in the retraction of membrane projections based on actin filaments, such as transzonal projections (TZPs). Conversely, we found that follicles from the ovary contralateral to the CL, which contained low intrafollicular P4 concentrations, had a high detection of proteins predicted to regulate the maintenance of TZPs. We also performed RNAseq analysis which demonstrated that 177 genes were differentially expressed in CC under the different P4 environments. Bioinformatic analysis points to changes associated to cell metabolism in cells from follicles ipsilateral to the CL in comparison to genes involved in cell communication in CC from follicles contralateral to the CL. Our functional analysis experiment confirmed that supplementation of cumulus-oocyte complexes during in vitro maturation with P4 at concentration similar to ipsilateral follicles reduces the number of TZPs. In summary, our study underscores a direct association between P4 concentration and cumulus-oocyte interaction, with potential consequences for the acquisition of oocyte competence.

P-608 Cumulative live birth rates after 3 consecutive embryo transfers in freeze-all cycles following gonadotropin-releasing hormone antagonist protocol versus progesterone-primed ovarian stimulation

Abstract Study question Do cumulative live birth rates in freeze-all cycles differ between gonadotropin-releasing hormone (GnRH) antagonist protocol and progesterone-primed ovarian stimulation (PPOS)? Summary answer GnRH antagonist and PPOS protocols have similar cumulative live birth rates in freeze-all cycles. What is known already GnRH antagonists and progesterone have been used for pituitary suppression in ovarian stimulation cycles. While PPOS protocol has the advantage of oral usage and lower cost, data regarding the laboratory and clinical outcome is limited and confounding. Freeze-all cycles might provide a better model to assess the impact of PPOS protocol and GnRH antagonist protocol on laboratory, clinical outcomes and cumulative live birth rates. Study design, size, duration A retrospective cohort study on IVF cycles performed (n = 568) between January 2020 and May 2022.The entire cohort of embryos were cryopreserved at the blastocyst stage.Inclusion criteria were 18-42 years of age,ICSI for severe male factor infertility.Exclusion criteria were PGD and severe endometriosis.Indications for cryopreservation in the antagonist group were high ovarian response (n:102),endometrial polyps (n:34),high follicular phase P4(n:48) and elective purposes(n:260).PPOS was used due to a transient shortage of GnRH antagonist in the market (n:124). Participants/materials, setting, methods 568 women (GnRH antagonist:444; PPOS:124) were included in the analysis.The primary outcome was the cumulative live birth rate (CLBR) after 3 consecutive embryo transfer cycle, and the secondary outcome parameters were the number of M-II oocytes, fertilization rate and blastocyst utilization rate. Student’s t-test was used for normally distributed continuous data and Fisher’s exact tests for categorical data were used. A generalized estimating equation model and logistic regression analysis were performed to adjust for confounding factors. Main results and the role of chance The mean age of the GnRH antagonist group was 34.1 ± 5.3 and 34.5 ± 5.7 years in PPOS group (p = 0.38). The baseline characteristics including BMI, serum AMH levels, duration of infertility, duration of stimulation and gonadotropin ampules used were similar in both groups. Estradiol and progesterone levels at the time of ovulation trigger were higher in GnRH antagonist cycles (2383.5 ± 1375.4 vs 2034.5 ± 1218.3, p = 0.02 and 0.7 ± 0.6 vs 0.5 ± 0.4, p = 0.01, respectively) The mean number of cumulus-oophorus complexes (12.9 ± 7.4 vs 11.5± 10.0, p = 0.61), M-II oocytes (10.0± 6.1 vs 9.1± 6.1, p = 0.14), frozen blastocysts (4.8± 3.5 vs 4.7± 3.6, p = 0.71) were similar between GnRH antagonist and PPOS groups, respectively. Fertilization rates (84.4% vs 87.2%, p = 0.12) and blastocyst utilization rates (63.4% vs 65.9%, p = 0.34) were also similar between GnRH antagonist and PPOS groups, respectively. The number of transferred embryos and the number of unused blastocysts were similar between groups. The CLBRs after one IVF cycle and 3 consecutive frozen-thawed blastocyst transfers were comparable in GnRH antagonist and PPOS cycles (56.8% and 53.2%, p = 0.37, respectively). Limitations, reasons for caution This was a retrospective study with relatively small sample size performed at a single fertility center, which may limit the generalizability of our findings. Wider implications of the findings If the fresh embryo transfer is not intended, PPOS protocol can be used in all patient types with cost-effective and patient-friendly manner. Trial registration number 2024.013.IRB2.012

P-429 Measuring serum progesterone levels on the day of a fresh blastocyst transfer is debatable as there is no evidence for correlation with ongoing pregnancy results

Abstract Study question Does serum progesterone (P4) level on the day of a fresh blastocyst transfer relate to ongoing pregnancy rate (OPR)? Summary answer OPR after a fresh single blastocyst transfer seems not to be associated with serum P4 level on the day of transfer. What is known already Several studies have suggested an optimal serum P4 threshold for embryo transfers in frozen embryo transfer cycles. However, for fresh embryo transfers, data are scarce and conflicting. Study design, size, duration A retrospective single-center cohort study was performed on 598 complete data cycles, retained out of 631 consecutive fresh single blastocyst transfer cycles. Data were collected from patients undergoing a fresh IVF/ICSI cycle with autologous oocytes at a tertiary fertility center between June 2022 and August 2023. Participants/materials, setting, methods A total of 482 unique patients underwent one or more single fresh blastocyst transfers using micronized vaginal progesterone (MVP) 800mg BID for luteal phase support starting day after oocyte retrieval. Serum P4 levels were determined on day of transfer. The primary endpoint was OPR, positive hCG-test and early pregnancy loss (EPL) were secondary endpoints. Unadjusted and adjusted generalized estimating equations (GEE) assessed P4 level association with the endpoints, using an exchangeable working correlation matrix. Main results and the role of chance No association was identified between P4 levels on day of transfer and OPR after accounting for maternal age, blastocyst quality, P4 and estradiol level at last ultrasound, BMI and endometrial thickness. Data were grouped according to 10/50/90 and 25/50/75 percentiles, resulting in groups &amp;lt; = or &amp;gt; 27ng/ml and &amp;lt; = or &amp;gt; 40ng/ml, with omission of 90th and 75th percentile groups due to right-skewed distribution. With serum P4 levels higher than 40ng/ml, the probability of a positive hCG-test significantly increased (OR 1.79, CI 1.11-2.91; p = 0.018). No significant difference was observed in patients with serum P4 &amp;lt; = or &amp;gt; 27ng/ml (OR 1.23, CI 0.66-2.30; p = 0.506). Regarding OPR, no significant differences were observed when comparing patients with serum P4 &amp;lt; = or &amp;gt; 27/ng/ml or &amp;lt; = or &amp;gt; 40ng/ml (OR 0.88, CI 0.42-18.85; p = 0.736 and OR 1.41, CI 0.83-2.37; p = 0.203, respectively). Moreover, EPL did not significantly differ between serum P4 level groups (OR 1.93, CI 0.61-6.13; p = 0.265 and OR 1.2, CI 0.51-2.84; p = 0.674). Age (p &amp;lt; 0.001) and embryo quality (p &amp;lt; 0.001) are significantly related with OPR. Additionally, late follicular progesterone levels and OPR are significantly associated (OR 2.39, CI 1.16-4.95 in patients with P4 &amp;lt; = or &amp;gt; 27/ng/ml and OR 2.21, CI 1.07-4.55 in patients with &amp;lt; =40ng/ml and &amp;gt;40ng/ml). Limitations, reasons for caution Limitations include the retrospective design and the lack of live birth outcome data. Progesterone levels exceeding 60 ng/ml were not further analyzed to their precise value but grouped as 60 plus which did not allow to identify potential detrimental effects of very high P4 levels on treatment outcome. Wider implications of the findings Our data suggest that measuring P4 on the day of a single blastocyst transfer with MVP luteal phase support may not be indicative of OPR or the risk of EPL. This raises questions regarding the necessity for routine P4 measurements as well as the development of rescue strategies. Trial registration number ONZ-2023-0628

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.

Effect of 200 μg of gonadorelin hydrochloride at the first GnRH of a CO-Synch program on ovulation rate and pregnancies per artificial insemination in Holstein heifers

The initial ovulatory response during synchronization programs is often low in dairy heifers, largely due to follicular dynamics and hormonal dynamics. Specifically, the progesterone (P4) concentration at the time of the first GnRH treatment in a breeding program can influence the LH response, often resulting in a suboptimal ovulatory response. The objective of this study was to determine the effect of the highest label dose 200 μg (100 μg vs. 200 μg) of GnRH (50 μg of gonadorelin hydrochloride per mL; Factrel, Zoetis Inc. Madison, NJ) at the first GnRH of a 6-d CO-Synch plus P4 device program on ovulatory response and pregnancy per AI (P/AI) in first service in Holstein heifers. A total of 1,308 Holstein heifers were randomly allocated at the beginning of a 6-d CO-Synch program at day 0 to receive either i.m. treatment of 100 μg (2CC, n = 655) or 200 μg (4CC, n = 653) of GnRH. Also, at d 0, heifers received an intravaginal insert with 1.38 g of P4 (Eazi-Breed CIDR Cattle Insert, Zoetis Inc.). On day 6, the insert was removed, and i.m. treatment of 25 mg of PGF2α (12.5 mg of dinoprost tromethamine/mL; Lutalyse HighCon Injection, Zoetis Inc.) was administered. On d 7, a second i.m. treatment of 25 mg of PGF2α was given, followed on d 9 by concurrent i.m. treatment of 100 μg of GnRH, and timed AI. A subset of 396 heifers had their ovaries scanned to evaluate ovulatory response, and blood samples were collected to measure the serum concentration of P4 at d 0 and d 6 of the study. The P4 concentrations at d 0 were categorized as low (≤3 ng/mL) or high (>3 ng/mL). The ovulatory response was greater for heifers receiving 4CC than 2CC at d 0 (54.7% vs. 42.8%). The ovulatory response was greater for low P4 than high P4 at d 0 (54.3% vs. 37.8%). However, we did not observe an interaction between treatment and P4 concentrations (low P4 2CC = 48.6% vs. high P4 2CC = 30.0%; low P4 4CC = 60.0% vs. high P4 4CC = 45.5%). The receiver operating characteristic curve analysis indicated that P4 concentrations at d 0 treatment could predict the ovulatory response, although the area under the curve was only 0.6. As expected, heifers that ovulated had increased P/AI (no = 55.6% vs. yes = 67.7%); however, we found no effect of treatment on P/AI (2CC = 63.3% vs. 4CC = 59.6%), and no interactions between treatment and ovulation and treatment and P4 (high vs. low) for pregnancy outcomes. In summary, P4 concentration and increasing the dose of GnRH at d 0 positively affected ovulatory response in Holstein heifers. However, there was no interaction between treatment and P4 on ovulation and no subsequent impact of GnRH dose on P/AI.

Influence of repeated estrus synchronization treatment on hormone secretion, growth, and development of dairy goats.

In large-scale intensive farms, dairy goats often undergo frequent estrus synchronization (ES) treatment, which may result in a decline in reproductive performance; however, the underlying mechanism remains unclear. The present study aimed to investigate the effect of pregnant mare serum gonadotropin (PMSG) and progesterone (P4)-mediated ES treatment on fertility in dairy goats, while also identifying key metabolic and endocrine mechanisms that influence reproductive performance in does subjected to repeated ES treatment. Forty-eight Saanen does were randomly assigned to two groups (24 goats each) that received ES treatments either thrice fortnightly (3-PMSG) or once (1-PMSG) simultaneously with the third ES treatment of the 3-PMSG group during the breeding season. ES treatment was performed via the intravaginal insertion of a controlled internal drug release (CIDR) device impregnated with 300 mg P4, followed by 300 IU PMSG injections 48 h before CIDR withdrawal. Blood was collected to detect the level of hormones and blood biochemical indices. Additionally, estrus rate, fecundity rate, body weight, size, and lactation performance were measured. The results showed that repeated ES treatment markedly decreased the estrus rate and fecundity rate of goats. Among the does in all groups, there was no substantial difference in follicle stimulating hormone, luteinising hormone, gonadotropin-releasing hormone, melatonin, growth hormone, PMSG, total cholesterol, total protein, and glucose levels, as well as the body weight, body size, and lactation performance. Repeated ES treatment elevated estrogen (E2) levels 36, 48, and 72 h post-CIDR removal; increased P4 upon CIDR insertion; and raised PMSG antibody levels 24, 48, and 72 h post-CIDR removal. The results suggest that elevated anti-PMSG levels are the primary reason for the decline in ES efficiency, and that high E2 and P4 levels at some time points also impair reproductive performance. These findings provide novel insights into the metabolic effects of repeated PMSG stimulation in goats, guiding future reproductive hormone use in breeding practices.

Possibility of early pregnancy detection in alpacas (Vicugna pacos) based on fecal steroid hormone concentrations.

Early pregnancy detection in alpacas, whose breeding season is limited to the rainy season and has a long gestation period, is important for reproductive management. Conventional detection methods such as ultrasonography cannot be used to detect pregnancy before 30 days after mating. In this study, we examined the feasibility of using fecal steroid hormones as an early detection method in pregnant and non-pregnant alpacas. Fecal and blood samples were collected from pregnant and non-pregnant alpacas after mating. Progesterone (P4) and estradiol 17-β were extracted and quantified from blood and fecal samples. A positive correlation exists between the steroid hormones in serum and feces, indicating that serum steroid hormone concentrations can be estimated from fecal steroid hormones. Within 10days after mating, both pregnant and non-pregnant alpacas had fecal P4 concentrations greater than 1.0ng/mg dry matter (DM), but by 15 days after mating, fecal P4 concentrations decreased to the pre-mating concentration in non-pregnant alpacas. From 15 days after mating, non-pregnant alpacas had a low fecal P4 concentration (< 1ng/mg DM), whereas a high fecal P4 concentration indicated the possibility of pregnancy, suggesting that this test is clinically beneficial as a supportive test for pregnancy detection.

Mammary Microvessels are Sensitive to Menstrual Cycle Sex Hormones.

The mammary gland is a highly vascularized organ influenced by sex hormones including estrogen (E2) and progesterone (P4). Beyond whole-organism studies in rodents or cell monocultures, hormonal effects on the breast microvasculature remain largely understudied. Recent methods to generate 3D microvessels on-chip have enabled direct observation of complex vascular processes; however, these models often use non-tissue-specific cell types, such as human umbilical vein endothelial cells (HUVECs) and fibroblasts from various sources. Here, novel mammary-specific microvessels are generated by coculturing primary breast endothelial cells and fibroblasts under optimized culture conditions. These microvessels are mechanosensitive (to interstitial flow) and require endothelial-stromal interactions to develop fully perfusable vessels. These mammary-specific microvessels are also responsive to exogenous stimulation by sex hormones. When treated with combined E2 and P4, corresponding to the four phases of the menstrual cycle (period, follicular, ovular, and luteal), vascular remodeling and barrier function are altered in a phase-dependent manner. The presence of high E2 (ovulation) promotes vascular growth and remodeling, corresponding to high depletion of proangiogenic factors, whereas high P4 concentrations (luteal) promote vascular regression. The effects of combined E2 and P4 hormones are not only dose-dependent but also tissue-specific, as are shown by similarly treating non-tissue-specific HUVEC microvessels.

FRI374 Immunomodulatory Effects Of Progesterone And Glucocorticoids In Pregnancy Immunity

Abstract Disclosure: A. Yasuda: None. T. Seki: None. H. Kashiwagi: None. N. Kitajima: None. Y. Kametani: None. Immune tolerance to a semi-allogeneic fetus is crucial for a successful pregnancy. However, the mechanisms of tolerance to semi-allografts in the co-existence with normal defenses against cancer and pathogens is not clear. During pregnancy, levels of pregnancy-related proteins and hormones such as progesterone (P4), estrogen, testosterone, and glucocorticoids (GC) increase. We hypothesized that the most abundant pregnancy related hormone in the placenta, P4, might play an important role in the local tolerance in the placenta. Thus, we aimed to compare the effects of P4 and cortisol (COR) on human lymphocytes in vivo, to clarify their role in the systemic regulation of immunity during pregnancy. Healthy donor peripheral blood mononuclear cells (PBMCs) were treated with P4 or COR for 6 h. These PBMCs were washed and transplanted intravenously into 8- to 9-week-old NOG-hIL-4-Tg (formal name, NOD.Cg-PrkdcscidIl2rgtm1Sug/Tg(CMV-IL4)/Jic) mice. Human epidermal growth factor receptor-2 (HER2) peptide was emulsified in complete Freund's adjuvant and administered intraperitoneally to these PBMC-NOG-hIL-4-Tg mice at the same day. As a negative control, an equal volume of PBS was added to the culture and transplanted into NOG-hIL-4-Tg mice. Boosters were administered using incomplete Freund's adjuvant 2 weeks after the primary immunization. Peripheral blood was collected 4 weeks after transplantation and 2 weeks after booster administration. T and B cell profiles were analyzed using FCM 28 days later. The results revealed that significantly higher numbers of human CD45+ cells engrafted in the spleens of P4-treated mice compared to COR-treated mice 4 weeks post-transplantation. Transplanted human CD45+ cells included T and B cells, and CD8+ T cells were significantly higher in P4-treated mice compared to both control and COR-treated mice. Moreover, antigen-specific IgG production was maintained in the P4-treated mice, suggesting that the T cell/B cell function was maintained in the mice. Compared to control and P4-treated mice, COR-treated mice tended to engraft fewer human CD45+ cells. Moreover, B cell engraftment tended to be lower in COR-treated mice than in control mice. Antigen-specific IgG production was not maintained. There results suggest that lymphocytes which experienced a high P4 environment maintain engraftment and function of human lymphocytes in the NOG-hIL-4-Tg mice, while high COR environment rather dampens the engraftment and function of them. The high-P4 environment limited in the placenta may support pregnant immunity to protect the semi-allogeneic fetus from pathogen-induced infectious disease or cancer. Presentation: Friday, June 16, 2023

The effect of progesterone concentrations during superovulation of Holstein heifers in a randomized trial

The aim of this study was to evaluate the effect of different progesterone (P4) concentrations during the follicular growth on the intensity of estrous expression, ovarian response to the superovulatory treatment, and embryo production and quality in superovulated heifers. A total of 63 Holstein heifers were randomly assigned into 2 experimental groups: Low P4 (n = 31) and High P4 (n = 32). Animals received a pre-synchronization protocol followed by a protocol of superovulation that included the allocated P4 treatment. Activity was monitored continuously by an automated activity monitor, and estrus characteristics (maximum intensity and duration) were recorded. Embryo collection was performed 7 d post artificial insemination (AI). Embryos were counted and graded from good or excellent (1) to degenerated (4). The outcomes of interest were: number and diameter of follicles at the time of AI, ovulation success (confirmed 7 d post-AI), time to estrus event, maximum intensity and duration of estrus, number and quality of embryos. Data were analyzed according to the type of outcome variable using logistic, linear, or Poisson regression models. A total of 105 embryos (High P4: n = 42; Low P4: n = 63) were graded for quality. Different P4 levels did not affect the maximum intensity (High P4 = 497.8 ± 23.9%; Low P4 = 542.2 ± 23.5%) or the duration (High P4 = 13.5 ± 1.5 h; Low P4 = 14.3 ± 1.4 h) of estrus. Heifers in the High P4 treatment had greater number of follicles at time of AI (High P4 = 16.6 ± 1.6 follicles; Low P4 = 13.9 ± 1.2 follicles), but with smaller diameter (High P4 = 11.3 ± 0.1 mm; Low P4 = 12.0 ± 0.1 mm) compared with Low P4. High P4 heifers tended to have better embryo quality compared with Low P4 heifers (odds ratio = 1.98; 95% CI = 0.90-4.35). High P4 heifers had less embryos than Low P4 heifers, but this was modified by the CIDR (intravaginal implant of P4) removal to estrus interval (interval 0-21 h: mean ratio = 1.15, 95% CI = 0.42-1.87; interval 22-46 h: mean ratio = 0.58, 95% CI = 0.27-0.96). Although estrous expression was not associated with embryo quality, as the duration and the maximum intensity of estrous expression increased, the number of embryos recovered 7 d post-AI increased (duration: mean ratio = 1.04; 95% CI = 1.03-1.05; maximum intensity: mean ratio = 1.50; 95% CI = 1.42-1.58). In conclusion, P4 during the follicular growth, and intensity of estrus, are playing a role in regulating the quality and the number of embryos produced by superovulated heifers. This study was supported by contributions from Resilient Dairy Genome Project and the Natural Sciences and Engineering Research Council.

Use of Doppler ultrasonography for selection of recipients in embryo transfer programs in horses

We aimed to evaluate the impact of corpus luteum (CL) and uterine characteristics accessed by B-mode and Color-Doppler ultrasonography in recipient mares at the time of embryo transfer (ET) on pregnancy outcomes. Recipient mares (n = 110), between days 3–9 after spontaneous ovulation, received a fresh embryo. Immediately before ET, the reproductive system was assessed by transrectal palpation for the following parameters: uterine tone (0–3), CL echogenicity (0–6), CL type (homogeneous, trabecular or anechoic center), luteal area (cm2), uterine echogenicity (0–3), uterine edema (0–3), luteal blood perfusion (0–100%) and uterine blood perfusion (1–4). Additionally, a blood sample was collected by puncture of the jugular vein for plasma P4 dosage. Retrospectively, recipients were classified according to the luteal area (small [≤ 6 cm2] or large [> 6 cm2]), luteal blood perfusion (low [≤ 55%] or high [> 55%]), and plasma concentration of P4 (low ≤ 9.98 ng/mL or high > 9.98 ng/mL). Pregnancy diagnosis was performed at 12 and 30 days of gestation. Luteal blood perfusion was significantly higher (P = 0.04) in pregnant recipients (n = 83) than in non-pregnant recipients (n = 27). Overall P/ET was higher (P ≤ 0.02) in mares with high luteal blood perfusion and high P4. Luteal blood perfusion was the most adequate significant (P = 0.01) predictor of pregnancy compared with the luteal area and plasma P4 concentration. Only luteal blood perfusion showed a linear (P = 0.03) and cubic (P = 0.004) effect on P/ET. In conclusion, CL blood perfusion determined by color-Doppler can be used in real-time to select recipients with the greatest chance of maintaining pregnancy in equine ET programs.

P-616 Evaluation of salivary ELISA for Oestradiol and Progesterone monitoring in IVF patients

Abstract Study question How do salivary E2 and P correlate with serum determinations across ovarian stimulation (OS) for IVF and artificial endometrial preparation cycles for embryo transfer? Summary answer Saliva-blood correlations were higher for E2 than for P. E2 saliva-blood ratios were patient-dependent. High serum P cases on trigger day could be identified. What is known already Steroid hormone concentrations in saliva are lower than in serum, even if the hormone is predominantly free. Therefore, quantitative assays need to be as sensitive as possible. Saliva-based assessments are a reliable and proven method for quantifying female hormone levels in premenopausal women during the natural cycle while being very precise and painless for patients. However, the cumulative experience in ovarian stimulation is relatively low. A recent study including 652 pairs of saliva-serum E2 samples reported correlations between 0.68 and 0.91, while 237 pairs of samples for P showed correlations ranging from -0.02 to 0.22 (Sakkas et al, 2020). Study design, size, duration Prospective cohort study including 300 saliva-blood pair samples from 120 patients undergoing OS for IVF (n = 90) or artificial endometrial preparation for embryo transfer (n = 30) between February and October 2022. Data were collected at each of 3 points of OS: early (days 1-5), mid (days 6-9), and trigger. Patients following endometrial preparation collected just one sample on the day of embryo transfer Participants/materials, setting, methods Thirty expected poor responders, 30 normal, and 30 expected high responders according to ovarian reserve evaluation were included. Two saliva samples per blood sample were collected: immediately after waking up, and at the clinic just before or after the blood sample was taken. Saliva samples were stored at -20ºC and shipped to Mint Diagnostics (Kent, UK) for analysis of salivary E2 and P4 Main results and the role of chance Saliva-blood E2 correlations (Spearman) were 0.68 (fasting) and 0.69 (clinic). 72% of individuals showed saliva-serum correlations &amp;gt; 0.8. Correlations improved when controlling for subgroup (low, normal, high responders). P4 saliva-blood correlations (Spearman) were 0.44 (fasting) and 0.29 (clinic). 41% of individuals showed correlations &amp;gt;0.8 on fasting samples, and 33% on clinic samples. There was a high variance of individual correlations (0-1), which were dependent on ovarian response subgroups (p &amp;lt; 0.05). A multivariable approach was developed to identify patients with a serum P4&amp;gt;1.5 ng/mL the day of trigger (n = 11) with clinic samples showing 81% sensitivity and 91% specificity and fasting samples showing 83% and 91% respectively demonstrating the possibility of shifting hormone analysis to the home rather than the clinic. Eighteen of 30 (60%) saliva samples collected on the day of ET on patients under hormonal replacement therapy showed values out of the assay range (&amp;gt;5000 pg/mL). Therefore, no correlations could be estimated. Limitations, reasons for caution Detection of patients with high P4 on the day of trigger was limited due to a short number of cases. No conclusions could be drawn in HRT patients for embryo transfer due to high salivary P4 values. Wider implications of the findings The current study shows that salivary monitoring of E2 and P4 is feasible. This more friendly non-invasive method could allow frequent hormone monitoring without the need for appointments at the clinic and for phlebotomy, thus resulting in more convenience for both the clinics and the patients. Trial registration number NCT05184777

Long-acting injectable progesterone treatment prior to puberty induction in gilts

Progesterone (P4) has a pivotal role on female puberty attainment in most farm animals. However, there are no studies evaluating the effect of P4 treatment previously to boar exposure for puberty induction in gilts. Therefore, serum P4 concentration, estrus expression and reproductive performance after boar stimuli were evaluated in gilts intramuscularly treated with long-acting P4 before boar exposure. In Experiment I, prepubertal gilts received either 1 mL of saline (control) or intramuscular (I.M.) P4 treatment (150 mg, 300 mg or 600 mg; n=6 per treatment). Serum P4 concentration for P4-treated gilts was greater than for control gilts for at least 8 d for P4300 and P4600 groups (P < 0.05), but greater until after 16 d only for those treated with 600 mg (P < 0.05). In Experiments II (prepubertal) and III (peripubertal), gilts received either saline (control) or 300 mg P4 I.M. and those showing estrus signs were artificially inseminated (AI), whereas gilts without estrus expression were culled. In prepubertal gilts (Exp. II), estrus expression rate did not differ (P < 0.05) for control (79.1%; n=110) and P4-treated gilts (81.5%; n=108). In peripubertal gilts (Exp. III), although estrus expression did not differ between control (77.6%; n=106) and P4-treated (69.6%; n=102) gilts (P > 0.05), P4-treated gilts presented longer (23.1 ± 1.4 days) interval from treatment to estrus expression than control gilts (17.1 ± 1.3 days; P < 0.05). In Experiments II and III, the proportion of culled gilts with ovarian structures consistent with normal estrous cycles, farrowing rate, and litter size did not differ between treatments (P > 0.05). In conclusion, I.M. treatment with 300 or 600 mg of long-acting P4 was efficient in maintaining high P4 concentrations in prepubertal gilts for at least 8 days. However, P4 treatment over this time interval did not benefit the reproductive performance of prepubertal and peripubertal gilts.

Doppler ultrasonography: an improvement in real-time recipient selection in equine ET programs

In this study, we test the hypothesis that a CL with greater blood perfusion has a more significant impact than luteal size and P4 concentrations on pregnancy per embryo transfer (P/ET). The study was carried out from November/2021 to May/2022 on a stud farm of the Mangalarga Marchador breed in Itaperuna-RJ, Brazil. Recipient mares (n=110), aged between 3-16 years, weighing 370-460 kg, with adequate BCS and on days 3 to 9 after spontaneous ovulation, received a single fresh grade I or II blastocyst, retrieved by uterine flushing of donor mares. Immediately before the ET, the CL characteristics were evaluated by B-mode and Color-Doppler ultrasonography (US) and a blood sample was collected for plasma P4 assay. Recipients were retrospectively classified according to CL area [small (≤6 cm2) or large (>6 cm2)], CL blood perfusion [low ≤55 % or high >55%] and plasma P4 concentration [low ≤9.98 ng/mL or high >9.98 ng/mL]. Pregnancy diagnosis was performed 30 days after ET and P/ET analysis was performed using the GLIMMIX of SAS procedure. The overall P/ET was 73% (83/110). The P/ET was not influenced by the luteal area, but effects of CL blood perfusion class (P=0.007) and the P4 plasma concentration class (P=0.02) on P/ET were observed. The P/ET was greater in the high luteal perfusion group [89.1%, 41/46 vs.65.6%, 42/64] and in the high P4 group [85.4%, 41/48 vs. 67.7%, 42/62]. When area, luteal blood perfusion and P4 concentration were compared with the probability of pregnancy through ROC curve analysis, luteal blood perfusion (AUC=0.66) was the most significant (P=0.01) predictor of pregnancy compared to area (AUC=0.53) and plasma P4 (AUC=0.60). Finally, recipients were grouped into four different groups by analyzing CL blood perfusion classes and P4 (high CLBP and high P4 vs. High CLBP and low P4 vs. low CLBP and high P4 vs. low CLBP and low P4) and compared with the P/ET using the Fisher test. P/ET differed between groups (P=0002), as indicated by the higher P/ET in the high CLBP and high P4 95% (19/20) and high CLBP and low P4 84.6% (22/26) groups, compared to animals with low CLBP and low P4 55.5% (20/36). In conclusion, although the P4 concentration is a potential indicator of pregnancy success, it cannot be used in real-time when selecting the most appropriate recipient in a commercial ET program. Also, luteal blood perfusion determined by Doppler-US is an innovative and easily accessible tool that can be used in real-time to select the recipients with the greatest chances of maintaining pregnancy in ET programs in horses.

Patterns of parent screen use, child screen time, and child socio-emotional problems at 5 years.

Digital media screens have become an essential part of our family life. However, we have insufficient knowledge about parental screen use patterns and how these affect children's socio-emotional development. In total, 867 Canadian parents of 5-year-old children from the TARGet Kids! Cohort (73.1% mothers, mean ± SD age=38.88 ± 4.45 years) participated in this study from 2014 to the end of 2019. Parents reported parental and child time on television (TV) and handheld devices and completed the Strengths and Difficulties Questionnaire (SDQ). Latent profile analysis identified six latent profiles of parent screen use: low handheld users (P1, reference; n=323), more TV than handheld (P2; n=261), equal TV and handheld (P3; n=177), more handheld than TV (P4; n=57), high TV and handheld (P5; n=38), and extremely high TV and handheld (P6; n=11). Parents that were more likely to belong to P6 were also more likely to be living in single-parent households compared to P1 (estimate=-1.49 ± 0.70), p=.03). High membership probability for P2 (estimate=-0.67 ± 0.32, p=.04) and P4 (estimate=-1.42 ± 0.40, p < 0.001) was associated with lower household income compared to P1. Children of parents with higher P4 (χ2 =12.32, p < 0.001) or P5 (χ2 =9.54, p=.002) membership probability had higher total screen time compared to P1. Finally, a higher likelihood to belong to P6 (χ2 =6.82, p=.009) was associated with a higher SDQ Total Difficulties Score compared to P1. Thus, patterns of parent screen use were associated with child screen use and child socio-emotional problems. The emerging link between parental screen use profiles and child behaviors suggests the need for more research on parent screen time.

A possible function of Nik-related kinase in the labyrinth layer of delayed delivery mouse placentas.

In mice and humans, Nik-related protein kinase (Nrk) is an X-linked gene that encodes a serine/threonine kinase belonging to GCK group 4. Nrk knockout (Nrk KO) mice exhibit delayed delivery, possibly due to defective communication between the Nrk KO conceptus and its mother. However, the mechanism of delayed labor remains largely unknown. Here, we found that in pregnant mothers with the Nrk KO conceptus, the serum progesterone (P4) and placental lactogen (PL-2) concentrations in late pregnancy were higher than those in the wild type. Moreover, we demonstrated that Nrk is expressed in trophoblast giant cells (TGCs) and syncytiotrophoblast-2 (SynT-2) in the labyrinth layer of the mouse placenta. In the human placenta, NRK is also expressed in Syn-T in villi. Both human Syn-T and mouse TGCs of the labyrinth layer are present within fetal tissues that are in direct contact with the maternal blood. The labyrinth layer of the Nrk KO conceptus was gigantic, with enlarged cytoplasm and Golgi bodies in the TGCs. To investigate the function of Nrk in the labyrinth layer, a differentially expressed gene (DEG) analysis was performed. The DEG analysis revealed that labor-promoting factors, such as prostaglandins, were decreased, and pregnancy-maintaining factors, such as the prolactin family and P4 receptor, were increased. These findings suggest that the Nrk KO mice exhibit delayed delivery owing to high P4 concentrations caused by the hypersecretion of pregnancy-maintaining factors, such as PL-2, from the placenta.

Effects of additional gonadotropin-releasing hormone and prostaglandin F2α treatment to an estradiol/progesterone-based embryo transfer protocol for recipient lactating dairy cows

This study was designed to evaluate whether the utilization of a second PGF2α treatment at the end of an estradiol/progesterone (E2/P4)-based protocol with or without GnRH at the beginning of the protocol would improve pregnancy rates of lactating Holstein cows assigned to timed embryo transfer. A total of 501 lactating Holstein cows in 5 farms were enrolled in the experiment. Within farm, cows were blocked by parity and, within block, were assigned randomly to (1) insertion of an intravaginal P4 device (controlled internal drug-releasing device; CIDR) and estradiol benzoate on d -11, PGF2α on d -4, CIDR withdrawal and an injection of estradiol cypionate on d -2, and timed embryo transfer on d 7 (1-PGF; n = 164); (2) the same treatments as 1-PGF, but with PGF2α administered on d -4 and -2 (2-PGF; n = 171); and (3) 2-PGF with the addition of a GnRH treatment on d -11 (GnRH+2-PGF; n = 166). Ovaries were scanned by transrectal ultrasonography on d -11, -4, and 7, and blood samples were collected on d -11, -4, 0, and 7 for P4 determination. Treatment comparisons were performed using contrasts. The proportion of cows with a new corpus luteum on d -4 was greater in GnRH+2-PGF cows. Cows in 1-PGF had a greater P4 concentration on d 0 but lesser P4 on d 7 compared with cows in the other groups. Cows assigned to receive 2-PGF (2-PGF and GnRH+2-PGF) had greater estrus expression, and a greater proportion of cows ovulated to estradiol cypionate. No further contrast effects were observed for follicle diameter, double ovulation rate, pregnancy per embryo transfer (P/ET) on d 32 and 60, or pregnancy loss. As P4 concentration on d -4 increased, P/ET on d 60 tended to increase. Cows with P4 ≥3.66 ng/mL on d -4 had greater P/ET on d 32 and 60 than those with P4 below that threshold. Regardless of treatment, cows with P4 concentration ≥3.66 ng/mL also had a greater pregnancy per synchronized protocol (P/SP) on d 60. Also, a P4 concentration on d -4 (low or high) × follicle diameter (continuous) interaction tendency was observed when evaluating P/ET. Although P/ET did not differ among cows with different follicles sizes with reduced P4 concentration on d -4 (<3.66 ng/mL), it increased in cows with larger follicles exposed to increased P4 concentration (≥3.66 ng/mL). When P4 on d 0 was evaluated, P/ET on d 32 and 60 was greater for cows with low (≤0.09 ng/mL) versus high (>0.21 ng/mL) P4; as P4 concentration on d 0 increased, P/ET linearly decreased. In summary, cows with increased P4 concentrations during growth of the ovulatory follicular wave had improved P/ET. Administering a second PGF2α dose reduced P4 concentration on d 0 and increased ovulatory response to the protocol, but no benefits were observed on P/ET or P/SP.

VERY HIGH SERUM PROGESTERONE LEVELS ON THE DAY OF EMBRYO TRANSFER DO NOT HAVE AN IMPACT ON OUTCOMES IN ARTIFICIALLY PREPARED FROZEN EMBRYO TRANSFER CYCLES

Low serum progesterone (P4) levels on the day of embryo transfer (ET) decrease the ongoing pregnancy rates in artificial cycles for frozen embryo transfer (FRET). It is not known whether very high P4 levels may be inducing any effect on clinical outcomes. Objective of this study is to determine whether there is an upper limit for serum P4 levels on the day of ET above which clinical outcomes are affected in artificially prepared FRET cycles.