Table 1. Ovulation and Clinical Outcomes by Obesity Status
JBRA Assisted Reproduction 2025;29(Suppl.2 SBRA 2025):161
Poster Presentation
29th Annual Congress of the SBRA. São Paulo/SP - Brazil, 2025
doi: 10.5935/1518-0557.20263928
P-149. Letrozole in ovulation induction for obese women undergoing timed intercourse
Amanda Lopes de Faria1, Maiara Peixoto Paiva1, Rivia Mara Lamaita1, Moisa Lúcia Pedrosa Correa da Silva1, Bruna Schettino Morato Barreira1
1 MATERDEI S/A - Belo Horizonte - MG – Brasil
Objective: Obesity can impair fertility through hormonal and metabolic alterations, even in women without PCOS. Letrozole, by stimulating ovulation without prolonged antiestrogenic effects on the endometrium, may improve follicular development and endometrial receptivity. This review aims to evaluate the efficacy of letrozole in obese women undergoing timed intercourse, assessing ovulation rates, endometrial parameters, and pregnancy outcomes.
Methods: A systematic search was conducted in PubMed and Google Scholar using the keywords "letrozole," "obesity," "ovulation induction" and "timed intercourse" Original studies published in English or Portuguese involving obese women undergoing ovulation induction with letrozole combined with timed intercourse were included. Exclusion criteria comprised other causes of infertility (such as tubal factor, endometriosis, and hormonal disorders unrelated to body weight), significant male factor infertility, and a diagnosis of polycystic ovary syndrome (PCOS). The search initially identified 9 articles, of which 3 were excluded for not meeting the inclusion criteria, resulting in 6 studies included for analysis.
Results: In obese women, endometrial thickness and vascularization may be naturally impaired due to systemic inflammation and hormonal alterations. Letrozole, by not exerting a prolonged antiestrogenic effect on the endometrium, may minimize this impairment and promote a more receptive pattern, which could contribute to maintaining conception rates similar to those observed in non-obese women. In PCOS, trials such as PPCOS II have demonstrated the superiority of letrozole over clomiphene citrate in ovulation and live birth rates, including in women with BMI ≥30 kg/m2. In unexplained infertility, a retrospective study with 135 women (≈30% without PCOS) undergoing letrozole + FSH with timed intercourse or intrauterine insemination showed similar pregnancy rates between obese and non-obese women (28.5% vs 29.2%; p=0.75), suggesting maintained efficacy.
Conclusion: Letrozole maintains good efficacy in obese women with PCOS, surpassing clomiphene, and shows pregnancy rates comparable to non-obese women in cases of unexplained infertility. In obese women, endometrial thickness and vascularization may be naturally impaired due to systemic inflammation and hormonal alterations. Letrozole, by not exerting a prolonged antiestrogenic effect on the endometrium, may minimize this impairment and favor a more receptive pattern. Specific prospective studies are needed to confirm its superiority in this subgroup.
Table 1. Ovulation and Clinical Outcomes by Obesity Status