P-500 Relationship of midluteal serum progesterone levels and pregnancy outcomes after day-3 embryo-transfer(ET) in hormonal replacement therapy (HRT) cycles with intramuscular progesterone: a prospective cohort study

Abstract

Abstract Study question Does midluteal(day-9 of progesterone) serum progesterone level in HRT cycles with intramuscular progesterone affect the clinical pregnancy rate (CPR)/early miscarriage rate(MR) and live birth rate(LBR)? Summary answer Midluteal serum progesterone between 32.2-43.7ng/ml results in significantly greater CPR versus that with lower/higher levels and significantly greater LBR compared to that with lower levels. What is known already Evidence points to low serum progesterone levels at the time of FET being associated with lower ongoing pregnancy rates. Recently, the relation of midluteal serum progesterone levels in HRT cycles with vaginal progesterone as luteal phase support (LPS) has been elaborated indicating better pregnancy outcomes with an optimum range of serum progesterone/higher levels. There is no data establishing the association of pregnancy outcomes with midluteal serum progesterone levels when intramuscular progesterone is used as LPS in HRT cycles. Study design, size, duration A prospective cohort study conducted between December 2019-March 2022 at a tertiary centre with 196 patients(204 cycles), both-autologus(AO)-56.3% and donor oocytes(DO)- 43.6%: fresh ET-16.6% and frozen ET(FET)-83.3% with similar ICSI, vitrification and ET protocols(2/3 Grade A day-3 embryos). CPR, early MR (≤13 weeks miscarriage/clinical pregnancy) and LBR (≥28 weeks, LBs/ETs) were compared. Serum progesterone was measured on the morning of day-5 post-ET(day 9th from the start of progesterone). Most patients delivered at the same institute. Participants/materials, setting, methods Patients were non-smokers with normal hysteroscopy. Oral estradiol 6-8mg was initiated from Day 1-2 (for 10-17 days). When ET ≥ 7mm and serum progesterone <1ng/ml, intramuscular progesterone 100mg/day was started (daily till day-4 post-ET, then every 3rd day till week 8). Vaginal progesterone gel was added from day 5 post-ET till week 10. Serum progesterone levels were categorized in tertiles. Chi-square, t-tests and multiple regression analysis was used for statistical analysis. Two-tailed P<.05 indicated statistical significance. Main results and the role of chance Mean age was 34.76±5.36 years with a mean BMI 26.4±4.38kg/m2 Overall, CPR was 106/204(51.9%), LBR 78/204(38.2%) and early MR 28/106(26.4%) Midluteal serum progesterone levels ranged from 11.1-261ng/ml and were divided into tertiles(T) T1<32.0ng/ml(n = 68),T2 32.2-43.7ng/ml(n = 68),T3 >43.7ng/ml (n = 68) Median progesterone levels of T1,T2,T3 were 27.7ng/ml(Interquartile range [IQR] 7.0), 38.4ng/ml (IQR 5.0) and 51.2ng/ml (IQR 12.6) respectively. Mean age and mean BMI was not significantly different across the tertiles P=.27, P=.20 respectively CPR was significantly different across T1 32/68(47%),T2 45/68(66.1%)and T3 29/68(42.6%) P=.014. CPR was significantly more in T2 versus T1 and T3, (OR:2.2, 95%CI:1.1-4.4 P =.02) and (OR:2.6,95%CI:1.3-5.3, P=.006), respectively. T3 versus T1, P =.60 LBR was also significantly different across the tertiles [T1 20/68(29.4%), T2 34/68(50%),T3 24/68(35.3%) P=.03] LBR in T2 was significantly more than in T1(OR: 2.4,95% CI:1.2-4.9, P=.02). There was no significant difference betweenT3 versus T1 and T2 versus T3, P=.46, P=.08, respectively. Early MR wasn’t significantly different across T1 12/32(37.5%), T2 11/45(24.4%) and T3 5/29(17.2%), P=.18 Serum progesterone levels were not significantly affected by age r = 0.0257, P=.71 or BMI r = 0.0097, P=.89 Multivariate logistic regression showed that age affected CPR after adjusting for BMI, midluteal serum progesterone levels, origin of oocytes, fresh ET/FET(AOR 0.92: 95% CI:0.86-0.98, P=.01). Limitations, reasons for caution This is a single centre study with limited sample size. Including the measurement of serum progesterone at the time of ET would have given a better perspective of the patient specific behavior of progesterone as LPS. Larger studies with different LPS protocols are needed to validate the results. Wider implications of the findings In HRT cycles with intramuscular progesterone, an optimum midluteal serum progesterone level is related to better pregnancy outcomes. Factors causing the wide variation of progesterone levels need to be evaluated so as to individualize the dose. Identifying the appropriate time frame for optimising the midluteal progesterone levels should be explored. Trial registration number not applicable