Obesity Linked to Lower IVF Pregnancy, Live Birth Rates

Obese women undergoing IVF have fewer normally fertilized oocytes, lower estradiol levels

WEDNESDAY, June 22 (HealthDay News) -- Women with a body mass index (BMI) of 40 kg/m² or more who undergo in vitro fertilization (IVF) have a significantly reduced likelihood of clinical pregnancy and live birth than women with normal BMI, according to a study published in the July issue of Obstetrics & Gynecology.

Divya K. Shah, M.D., from the Brigham and Women's Hospital and Harvard Medical School in Boston, and colleagues assessed the impact of BMI on oocyte and embryo parameters and cycle outcomes in women undergoing IVF. Between 2007 and 2010, a retrospective cohort of 1,721 women undergoing a first IVF cycle with fresh, autologous embryos in an academic infertility practice was evaluated. Outcomes measured included the number of mature and normally fertilized oocytes, embryo morphology, estradiol levels on the day of human chorionic gonadotropin administration, clinical pregnancy, spontaneous abortion, and live birth rates.

The investigators found that, despite having similar numbers of mature oocytes, obese women with a BMI of 35 to 39.9 kg/m² or 40 kg/m² or higher had significantly fewer normally fertilized oocytes compared to women with normal BMI (7.6 and 7.7, respectively, compared with 9.3), and lower estradiol levels (1,498 and 1,361, respectively, compared with 2,047 pg/mL), after adjusting for age. Women with a BMI of 40 kg/m² or higher had a 50 percent lower likelihood of clinical pregnancy (odds ratio [OR], 0.50) and live birth (OR, 0.51) than women with normal BMI.

"Obesity was associated with fewer normally fertilized oocytes, lower estradiol levels, and lower pregnancy and live birth rates. Infertile women requiring IVF should be encouraged to maintain a normal weight during treatment," the authors write.

One of the study authors disclosed a financial relationship with the medical device industry, and two authors disclosed financial ties to a medical publishing company.

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