Slightly Elevated Progesterone on HCG Trigger Day Has an Impact on Pregnancy Outcomes of Fresh Single Blastocyst Transfer Cycles Under an Early Follicular Phase Prolonged Protocol Cycle

BACKGROUND: The effect of premature progesterone elevation on assisted reproductive technology has been debated. In different ovarian stimulation protocols, ovarian responses, and embryos transferred, conflicting results reside regarding the impact of elevated progesterone on pregnancy outcomes, according to previous studies. In addition, most studies have focused on significantly elevated progesterone levels, eg, above 1.5ng/mL, 1.75ng/mL, 2ng/mL. However, studies focusing on levels that are just slightly elevated are lacking, and some have concluded that such levels have no adverse effects on pregnancy outcomes. METHODS: Clinical data of patients who underwent early follicular phase prolonged protocol cycle in vitro fertilization/intracytoplasmic sperm injection treatment were collected. Patients were divided into two groups according to progesterone level on the trigger day of human chorionic gonadotropin (HCG): Group 1: < 1.0ng/mL and Group 2: 1.0–1.5ng/mL. Differences in baseline characteristics, ovulation promotion, and embryo culture, along with clinical pregnancy outcomes, were compared between the two cohorts. RESULTS: A total of 743 participants were included in this study, of which 587 were included in Group 1 and 156 were included in Group 2. In terms of pregnancy outcomes, Group 2 had a significantly lower clinical pregnancy rate and live birth rate per cycle than Group 1 (64.1% vs 75.7%, p < 0.05; 63.5% vs 72.7%, p < 0.05). After correction for maternal age, maternal body mass index, infertility duration, basal follicle-stimulating hormone, anti-Müllerian hormone, antral follicle count, total dose of gonadotropin, days of stimulation, and estradiol level on HCG trigger day, slightly elevated progesterone levels (P > 1.0ng/mL) remained a risk factor for pregnancy failure in fresh single D5 blastocyst transfer under an early follicular phase prolonged protocol cycle. CONCLUSION: Slightly elevated progesterone levels on HCG trigger day may negatively affect pregnancy outcomes in early follicular phase prolonged protocol cycles.