CYP19A1 and Infertility: In a study comparing occurrence of pregnancy among obese (body mass index: BMI > 30) and nonobese (BMI <30) infertile women (n = 90) with different etiologies, ovulation induction with the aromatase inhibitor letrozole (5 mg on menstrual cycle days 3–7) followed by intrauterine insemination (IUI).