The following is a summary of the “Luteal phase support with progesterone does not improve pregnancy rates in patients undergoing ovarian stimulation with letrozole,” published in the January 2023 issue of Reproductive Biomedicine Online by Dilday, et al.

Patients who had ovarian stimulation with letrozole in combination with intrauterine insemination (IUI) or timed intercourse (TIC) between January 2018 and October 2021 were included in this retrospective cohort study. Clinical pregnancy rate (CPR) was determined as the primary outcome for cycles treated with or without luteal phase progesterone support. Predictor variables for CPR were analyzed using univariate logistic regressions. 

Multivariate analysis was performed to determine the association between luteal progesterone use and the likelihood of clinical pregnancy, considering age, body mass index, anti-Müllerian hormone concentration, ovulatory dysfunction diagnosis, and multi-follicular development. Spontaneous abortion, biochemical pregnancy, and ectopic pregnancy were calculated as secondary outcomes. The secondary analysis determined the rate of live births per cycle. There were a total of 273 patients and 492 letrozole ovarian stimulation cycles. While 105 (21.3%) of these cycles did not use vaginal progesterone, 387 (78.7%) did. Without adjusting for confounding variables, the CPR per cycle was 11.6% (45/387) with progesterone and 13.3% (14/105) without (P = 0.645). 

The odds of clinical pregnancy were not significantly increased in cycles with exogenous progesterone (odds ratio [OR] 1.15, 95% confidence interval [CI] 0.48-2.75, P = 0.762), even after adjusting for significant covariates such as age, BMI, diagnosis of ovulatory dysfunction, and multi follicular development. The subsequent analysis showed that the live birth rate was 10.7% (41/384) with luteal progesterone and 12.5% (13/104) without it (P = 0.599). In ovarian stimulation cycles utilizing letrozole, luteal support with vaginal progesterone does not noticeably improve CPR.