Body mass index-associated differences in response to ovulation induction with letrozole.

OBJECTIVE

To compare occurrence of pregnancy among obese (body mass index [BMI] ≥30) and nonobese (BMI <30), infertile women undergoing ovulation induction with the aromatase inhibitor letrozole followed by intrauterine insemination (IUI).

DESIGN

Retrospective cohort study.

SETTING

Academic reproductive endocrinology and infertility clinic.

PATIENT(S): Ninety women with a variety of infertility diagnoses.

INTERVENTION(S): Letrozole (5 mg) on menstrual cycle days 3-7, followed by intrauterine insemination (IUI).

MAIN OUTCOME MEASURE(S): Occurrence of pregnancy and pregnancy outcomes.

RESULT(S): Ninety women underwent 180 letrozole-IUI cycles. Conception of pregnancy occurred in 10.4% and 18.2% of the BMI <30 and BMI ≥30 groups, respectively. Using BMI as a continuous variable showed a pregnancy odds ratio of 1.093 (confidence interval 1.008-1.184) for each unit increase in BMI. Incidence of miscarriage, multiple births, number of mature follicles, and presence of LH surge were similar between groups.

CONCLUSION(S): Our study of 90 women undergoing letrozole-IUI treatment showed greater likelihood of pregnancy in higher-BMI women, although the difference was not significant. Letrozole is an effective ovulation induction agent in higher-BMI women.