Influence of female bodyweight on IVF outcome: a longitudinal multicentre cohort study of 487 infertile couples

Abstract

This study investigated the impact of women’s body mass index (BMI) on the outcome after consecutive IVF/intracytoplasmic sperm injection cycles in 487 patients initiating treatment with 5-year follow-up. The total number of cycles was 1417. In total 103 (21.1%) were overweight (BMI 25–29.9 kg/m 2) and 59 (12.1%) were obese (BMI ⩾30 kg/m 2). Number of initiated cycles/woman ( P = 0.01), number of cancelled cycles/woman ( P < 0.01) and the total dose of gonadotrophin used/cycle ( P < 0.01) rose with increasing BMI. A negative linear association between BMI and the number of retrieved oocytes ( B = −0.243, P < 0.001) and an inverse U-shaped relationship between BMI and the number of developed embryos was seen, with less embryos available among underweight and obese women ( P = 0.03). The number with positive serum human chorionic gonadotrophin/cycle decreased significantly with increasing BMI ( P < 0.01). The ongoing pregnancy rate/cycle among the obese women was lower (20.8% versus 28.3% in normal-weight women; P = 0.04). Live-birth rate per cycle was 15.2% versus 21.5%. Multiple logistic regression analysis showed that the only independent predictors of live birth were women’s age ( P = 0.037), women’s BMI ( P = 0.034) and men’s age ( P = 0.040). The purpose of the study was to investigate the impact of women’s body weight on the outcome after repetitive IVF treatments. We included 487 patients initiating IVF treatment at four public IVF clinics in Denmark and all patients were followed for 5 years. The total number of treatment cycles was 1417. In total 103 (21.1%) were overweight (body mass index (BMI) 25–29.9 kg/m 2) and 59 (12.1%) were obese (BMI ⩾ 30 kg/m 2). The average number of started treatment cycles per woman, the mean number of cancelled cycles per woman and the total dose of ovarian stimulating hormone used per cycle rose with increasing female BMI. We observed that the higher the women’s BMI was, the lower was the number of oocytes collected during the treatment. Further we found that the number of developed embryos was highest in the normal-weight group, while the underweight and overweight groups developed fewer embryos. The number of positive pregnancy tests per treatment declined with increasing BMI and the rate of clinical pregnancies on ultrasound in week 7 was lower in obese women than among normal-weight women (20.8% versus 28.3%) and live-birth rate per cycle was 15.2% versus 21.5% in obese versus and normal-weight groups, respectively. Outcomes after IVF treatment including pregnancy and live-birth rates were lower in normal-weight versus obese women.