CONGENITAL ANOMALIES AFTER FIRST-TRIMESTER DYDROGESTERONE THERAPY DURING IN VITRO FERTILIZATION

To analyze the presence of congenital anomalies in children born after first-trimester dydrogesterone therapy during in vitro fertilization. Retrospective cohort study. Infertile women who underwent embryo transfer between 2010 and 2018 (80,103 fresh cycles and 44,712 frozen cycles) were included. We divided the patients into dydrogesterone-exposed group (group 1) and dydrogesterone-unexposed group (group 2) . The number of newborns was 52,175. The total number of congenital anomalies in group 1 was significantly lower than that in group 2 (105 [6.05‰] vs. 274 [7.90‰]; P = 0.020). The incidence of congenital musculoskeletal system malformations was also lower in group 1 (0.63‰ vs. 1.33‰; P = 0.025). After adjustment, there was no significant difference in the percentage of total congenital anomalies between the two groups (P = 0.972; odds ratio: 0.98; 95% CI: 0.59–1.62). However, the incidence of congenital anomalies of the musculoskeletal system remained lower in group 1 (P = 0.020; odds ratio: 0.2; 95% CI: 0.06–0.79), regardless of frozen or fresh cycles. After adjustment, dydrogesterone was associated with an increased incidence of genital birth defects (P = 0.028; odds ratio: 8.35; 95% CI: 1.25–54.68). However, this difference disappeared when the data were stratified by the number of frozen or fresh cycles. First-trimester dydrogesterone therapy did not increase the risk of congenital anomalies. Dydrogesterone might be associated with a reduced incidence of congenital anomalies of the musculoskeletal system, especially in frozen cycles.