In PCOS, which ovulation induction agent has shown superior live birth rates in some trials?

• A. Clomiphene
• B. Letrozole
• C. Gonadotropins
• D. Metformin

Answer: (B)

Letrozole is an oral aromatase inhibitor that works by lowering estrogen production. The drop in estrogen reduces negative feedback on the hypothalamus and pituitary, leading to increased FSH release and better follicular development. It tends to result in a favorable endometrial environment and fewer antiestrogenic effects than clomiphene, which can impair the endometrium and cervical mucus. In PCOS, several randomized trials have shown higher live birth rates (and often higher pregnancy rates) with letrozole compared to clomiphene, making it a more effective option for inducing ovulation with better ultimate outcomes. Gonadotropins can induce ovulation but come with higher risks of ovarian hyperstimulation and multiple pregnancies, and metformin alone is not an ovulation-inducing agent. So letrozole is the best choice among the options.