Obesity and in vitro fertilization: negative influences on outcome

To determine the influence of body mass index (BMI) on in vitro fertilization (IVF) outcome by studying a large cohort of good-prognosis IVF patients.

This was a retrospective study at a university-based IVF center evaluating 920 good-prognosis patients (< 40 years, all with normal ovarian reserve) undergoing luteal leuprolide down-regulation and gonadotropin stimulation for IVF and evaluating IVF outcome, including response to stimulation, cancellation rates and pregnancy outcome based on obesity status.

One hundred forty-eight (16.09%) patients were classified as obese (BMI > 27). Obese patients were more likely to undergo cancellation (14.9% vs. 9.1%, p = 0.03) when compared to nonobese patients. There was no difference in the amount of gonadotropins required. Obese patients had fewer oocytes retrieved and lower peak estradiol levels than did nonobese patients. In spite of the lower response, the clinical pregnancy rates per retrieval were no different (56.4% for both groups).

Obese patients undergoing IVF are more likely to undergo cancellation. If cancellation does not occur, obesity confers a risk of a lower stimulation response. Despite this, the clinical pregnancy rates (per retrieval) were no different in obese patients and nonobese patients.