P-640 Impact of adding oral dydrogesterone (OD) in patients with low serum progesterone (P) levels in artificially prepared frozen embryo transfer cycles (FET-HRT)

Abstract Study question In case of low serum P on the day FET (PFET), does addition OD to micronized vaginal progesterone (MVP) normalise reproductive outcomes? Summary answer PFET, adding results in ongoing pregnancy rates (OPR) comparable those patients who had normal PFET. What is known already Low PFET associated with increased early loss (EPL) and reduced live birth HRT cycles. While subcutaneous injections has been shown normalize clinical outcomes it unknown whether a similar effect. design, size, duration This retrospective, single-centre cohort study tertiary IVF-clinic. 694 unique single blastocyst transfer an cycle were included. As soon as endometrial thickness ≥ 6.5mm was reached following estradiol valerate priming, MVP (400mg,twice daily) started, followed by 6thday MVP. All underwent measurement just prior FET. Serum analysed using validated electrochemiluminescence immunoassay (Cobas 6000®,Roche). Participants/materials, setting, methods Clinical PFET(≥8,8ng/dl) routine MVPsupplementation compared PFET(<8,8ng/dl) whom OD(30mg TID) added from onwards. Primary outcome OPR, defined vital intra-uterine at 8 weeks. EPL biochemical or miscarriage. A multivariate regression model developed adjusting for age, BMI, thickness, embryo quality level. Main role chance Mean age MVP-only versus MVP+OD group 34.6(±4.2) 33.6(±4.3) years, respectively (p = 0.01). No other statistically significant differences seen among both groups nor quality. level observed 547/694 (78.8%) patients, continued planned, whereas detected 147/694 (21.2%) received additional supplementation next The mean 14.6 (±5.8) ng/ml 7.0(±1.8) group. OPR between groups: 40.8% only 40.0% 0.86). 55.0% 60.5% 0.23) 14.4% 21.1% 0.05) vs. group, respectively. Multivariate logistic analysis indicated that not investigated approaches (OR 0.92, SD 0.18, CI 0.63-1.35, p 0.68). Only significantly 3.03, 1.11, 1.48-6.21, 0.002). Limitations, reasons caution main limitation retrospective nature this risk unmeasured confounder bias. less robust parameter LBR, LBR data will be presented once available. Wider implications findings Additional gives rise OPRs P. Prospective studies are required identify individualized luteal phase support strategy combines optimal rates. Trial registration number Not Applicable