Effect of Obesity on Oocyte and Embryo Quality in Women Undergoing In Vitro Fertilization Divya K. Shah, MD, Stacey A. Missmer, ScD, Katharine F. Berry, MA, Catherine Racowsky, PhD, and Elizabeth S. Ginsburg, MD OBJECTIVE: To estimate the effect of body mass index (BMI) on oocyte and embryo parameters and cycle out- comes in women undergoing in vitro fertilization (IVF). METHODS: We evaluated a retrospective cohort of 1,721 women undergoing a first IVF cycle with fresh, autologous embryos between 2007 and 2010 in an aca- demic infertility practice. Main outcome measures in- cluded number of mature and normally fertilized oocytes, embryo morphology, estradiol on the day of human chorionic gonadotropin administration, clinical pregnancy, spontaneous abortion, and live birth. We performed multivariable analyses, adjusting for potential confounders, including age at cycle start, infertility diag- nosis, type of stimulation, total gonadotropin dose, use of intracytoplasmic sperm injection, and number of em- bryos transferred. RESULTS: Compared with women of normal BMI, women with class II (BMI 35–39.9) and III (BMI 40 or higher) obesity had fewer normally fertilized oocytes (9.3 compared with 7.6 and 7.7, P<.03) and lower estradiol levels (2,047 pg/mL compared with 1,498 and 1,361, P<.001) adjusting for age and despite similar numbers of mature oocytes. Odds of clinical pregnancy (odds ratio [OR] 0.50, 95% confidence interval [CI] 0.31– 0.82) and live birth (OR 0.51, 95% CI 0.29 – 0.87) were 50% lower in women with class III obesity as compared with women of normal BMI. CONCLUSION: Obesity was associated with fewer nor- mally 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. (Obstet Gynecol 2011;118:63–70) DOI: 10.1097/AOG.0b013e31821fd360 LEVEL OF EVIDENCE: II T he increasing prevalence of obesity among chil- dren and adolescents has resulted in higher num- bers of overweight and obese adults of reproductive age. 1 The deleterious effects of obesity on spontane- ous reproduction are well recognized, 2,3 although the literature on obesity and assisted reproductive tech- nology outcome remains heterogeneous and inconsis- tent. A 2007 review concluded that overweight and obese women with body mass indexes (BMI) 25 or greater have lower pregnancy rates after in vitro fertilization (IVF), require higher doses of gonadotro- pins to achieve sufficient ovarian response, and have higher miscarriage rates; however, the authors con- cluded that there was insufficient evidence regarding the effect of BMI on cycle cancellation, oocyte recov- ery, and live birth. 4 Little is known regarding the mechanisms by which obesity exerts its negative effect on reproduc- tive outcome. Prior studies in women using donor oocytes have been inconsistent with most showing no change in pregnancy rate among obese recipients, 5–7 but with others demonstrating a subtle decrease in the rate of ongoing pregnancy 8 –10 with increasing recipi- ent BMI. Additionally, most studies exploring the effect of obesity on infertility have focused exclusively on clinical outcomes such as pregnancy rate or im- From the Division of Reproductive Medicine, Department of Obstetrics, Gyne- cology, and Reproductive Biology, and the Channing Laboratory, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, and the Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts. Corresponding author: Divya K. Shah, MD, Division of Reproductive Endocri- nology and Infertility, Department of Obstetrics, Gynecology, and Reproductive Medicine, Brigham and Women’s Hospital and Harvard Medical School, 75 Francis Street, Boston, MA 02115; e-mail: dkshah@partners.org. Financial Disclosure Catherine Racowsky is on the Scientific Advisory Board of Origio and receives royalties from UpToDate. E.S.G. receives royalties from UpToDate. The other authors did not report any potential conflicts of interest. © 2011 by The American College of Obstetricians and Gynecologists. Published by Lippincott Williams & Wilkins. ISSN: 0029-7844/11 VOL. 118, NO. 1, JULY 2011 OBSTETRICS & GYNECOLOGY 63