Controlled Ovarian Hyperstimulation (COH) is crucial in Assisted Reproductive Techniques (ART), as it determines the number of mature oocytes retrieved, a key factor in pregnancy success. Serum estradiol (E2) is commonly used alongside transvaginal ultrasound (TVUS) to monitor ovarian response, but its accuracy is limited due to secretion from multiple follicular categories. In contrast, serum Inhibin A, primarily secreted by mature antral follicles, may offer a more accurate reflection of follicular maturity.

This retrospective study involved women undergoing COH for in vitro fertilization (IVF) using an antagonist protocol. Serum levels of E2 and Inhibin A were measured on the day of hCG trigger. The study assessed their association with ovarian response, specifically the number of mature follicles and mature oocytes retrieved.

The study included 84 IVF cycles. The total number of oocytes retrieved and the number of mature oocytes were significantly correlated with serum levels of Inhibin A (R² = 0.253 and R² = 0.267, respectively; p < 0.001) and estradiol (R² = 0.344 and R² = 0.259, respectively; p < 0.001). The correlation with Inhibin A strengthened with increasing follicular size, while the correlation with estradiol remained stable.

These findings suggest that serum Inhibin A, combined with transvaginal ultrasound, could help improve the timing of the hCG trigger. It may offer a more accurate assessment of follicular maturity compared to estradiol alone. Further studies are needed to confirm its role in routine IVF monitoring.