Luteal phase support with progesterone does not improve pregnancy rates in patients undergoing ovarian stimulation with letrozole.

RESEARCH QUESTION: Does luteal phase support with vaginal progesterone improve clinical pregnancy rates in patients undergoing ovarian stimulation with letrozole?

DESIGN

This was a retrospective cohort study of patients undergoing ovarian stimulation with letrozole paired with intrauterine insemination (IUI) or timed intercourse (TIC) from January 2018 to October 2021. The primary outcome of clinical pregnancy rate (CPR) was calculated for cycles with and without luteal phase progesterone support. Univariate logistic regressions were done to evaluate predictor variables for CPR. Clinically important covariates including age, body mass index, anti-Müllerian hormone concentration, diagnosis of ovulatory dysfunction and multifollicular development were included in a multivariate analysis evaluating the relationship between luteal progesterone use and odds of clinical pregnancy. Secondary outcomes including spontaneous abortion, biochemical pregnancy and ectopic pregnancy were calculated. Live birth rates were calculated for cycles in a secondary analysis.

RESULTS

A total of 492 letrozole ovarian stimulation cycles in 273 patients were included. Of these cycles, 387 (78.7%) used vaginal progesterone for luteal support and 105 (21.3%) did not. The unadjusted CPR per cycle was 11.6% (45/387) with progesterone and 13.3% (14/105) without progesterone (P = 0.645). After adjusting for significant covariates including age, BMI, diagnosis of ovulatory dysfunction and multifollicular development, the odds for clinical pregnancy were not significantly improved in cycles with exogenous progesterone (odds ratio [OR] 1.15, 95% confidence interval [CI] 0.48-2.75, P = 0.762). A follow-up analysis demonstrated that live birth rate was 10.7% (41/384) with and 12.5% (13/104) without luteal progesterone, respectively (P = 0.599).

CONCLUSIONS

Luteal support with vaginal progesterone does not significantly improve CPR in ovarian stimulation cycles using letrozole.