Researchers have found that adding letrozole (a drug widely used in breast cancer treatment) to a standard IVF (in vitro fertilization) hormone protocol improves live birth in women who respond poorly to ovarian stimulation.
Published in Reproductive and Developmental Medicine, the study by researchers at Dongguan Maternal and Child Healthcare Hospital compared outcomes in 176 women classified as poor ovarian responders. All participants were aged 35–42 and had limited ovarian reserve.
In IVF, the ovaries are stimulated with hormones to produce multiple eggs for fertilisation. Some women, particularly those over 35 or with diminished ovarian reserve, respond poorly to this stimulation despite receiving high doses. Simply increasing hormone dosage does not improve outcomes and can add cost and side effects. Finding more suitable ways to stimulate the ovaries in this group has been a major challenge in reproductive medicine.
Letrozole is an aromatase inhibitor, a drug that blocks the conversion of androgens into oestrogen. The research found that women who received letrozole alongside the standard gonadotropin-releasing hormone (GnRH) antagonist protocol needed significantly less hormone medication and completed stimulation about two days sooner than those on the standard protocol alone. More importantly, they produced a higher proportion of mature, fertilisable eggs and a greater number of high-quality embryos. Live birth rates were around 23.7% in the letrozole group compared to 11% in the standard group. Further analysis showed that women in the letrozole group were 2.6 times more likely to achieve a live birth.
When the letrozole group was analysed by age, women aged 35–38 achieved a clinical pregnancy rate of 60% and a live birth rate of 44%, compared to 25.5% and 13.7% respectively in women aged 39–42. "Even though we find that letrozole improves the overall outcomes, younger patients with poor ovarian reserve stand to benefit the most," the authors mentioned.
The authors call for larger, multicentre randomised trials to confirm these findings across a broader population. If validated, the addition of letrozole could offer a more cost-effective and clinically effective IVF pathway for one of the most challenging groups of patients in reproductive medicine.
