A Comprehensive Analysis of Body Mass Index Effect on in Vitro Fertilization Outcomes

The effect of a raised body mass index (BMI) on the outcome of assisted reproduction technology (ART) still represents a controversial issue. Even less clear is whether BMI acts with a potential detrimental effect on IVF outcomes via a deleterious effect on innate quality of oocytes or on the environmental milieu within the uterus. With the aim to better understand the mechanisms underlying the potential deleterious effect of an increased BMI on IVF outcomes, we have evaluated the effects of female BMI on number and quality of retrieved oocytes, fertilization rate, embryo score and incidences of ongoing pregnancy and live births among couples undergoing IVF in an Italian population. Data from 1602 women who underwent their first IVF cycle were retrospectively analyzed. A significantly reduced percentage of mature oocytes when comparing obese (BMI ≥ 30 kg/m²) and normal-weight patients (BMI = 18.50-24.99 kg/m²) was found. After adjusting for maternal age and other confounders, odds for ongoing pregnancy rate showed no differences across different BMI categories. However, a significant increased odds ratio (OR) could be observed for miscarriage rate in patients with BMI ≥ 25 (OR = 2.5; p = 0.04). These results should be taken into account in order to define optimal strategies for overweight and obese patients referring to ART procedures.