The impact of increasing body mass index on in vitro fertilization treatment, obstetrical, and neonatal outcomes

Background Citing the risks of administering anesthesia to patients with obesity, few fertility centers offer IVF as a treatment modality for patients with BMIs ≥ 40 kg/m2. Although previous studies have assessed clinical pregnancy and cumulative live birth rates in patients who spontaneously conceive with BMIs ≥ 50 kg/m2, there is a paucity of IVF, obstetric, and neonatal outcome data in patients with severe obesity who conceive after IVF. Objective To evaluate the impact of increasing BMI on IVF, obstetrical, and neonatal outcomes in patients with obesity undergoing IVF. Study Design This was a retrospective cohort study within an academic fertility center including 2,069 fresh IVF/ICSI and frozen embryo transfer cycles from January 1, 2012 to April 30, 2020: this cohort was utilized to determine IVF treatment outcomes. A second embedded cohort of 867 fresh IVF/ICSI and frozen embryo transfer cycles which resulted in ongoing clinical pregnancies and deliveries within a single tertiary hospital system was utilized to determine pregnancy, maternal, and neonatal outcomes. All patients with a BMI ≥ 40 kg/m2 underwent consultation with a maternal fetal medicine specialist prior to starting treatment and a preoperative evaluation with an anesthesiologist prior to oocyte retrieval. Cycles were grouped by body mass index at cycle start: BMI 30-34.9 kg/m2, BMI 35-39.9 kg/m2, BMI 40-44.9 kg/m2, BMI 45-49.9 kg/m2, and BMI > 50 kg/m2. Log-binomial Poisson regression and Poisson regression with an offset models were performed with BMI 30-34.9 kg/m2 as the reference group, adjusting for potential confounders including oocyte age, patient age, embryo quality, transfer type, and coexisting comorbidities. The primary outcome was live birth rate. Secondary outcomes included fertilization rate, blastulation rate, miscarriage rate, incidence of preeclampsia with severe features, gestational diabetes, labor induction, cesarean section, preterm delivery, and birth weight. Results There were 2,069 fresh IVF/ICSI and frozen embryo transfer cycle starts from January 1, 2012 to April 30, 2020. Of these, 1008 cycles were in the BMI 30-34.9 kg/m2 group, 547 in the BMI 35-39.9 kg/m2 group, 277 in the BMI 40-44.9 kg/m2 group, 161 in the BMI 45-49.9 kg/m2 group, and 76 in the BMI > 50 kg/m2 group. Live birth rate was not significantly different between groups. The BMI > 50 kg/m2 group was significantly more likely to experience preeclampsia with severe features when compared to the BMI 30-34.9 kg/m2 group (aRR 2.75, 95% CI 1.13-6.67). Fertilization rate, blastulation rate, miscarriage rate, incidence of gestational diabetes, labor induction, cesarean section, preterm delivery, and neonatal birth weights were not significantly different between groups. Conclusion (s): Among patients with BMIs 30-60 kg/m2 who conceived via IVF and received comprehensive prenatal care at a tertiary care hospital, IVF, obstetrical, and neonatal outcomes were largely comparable. These data support a collaborative care approach with maternal fetal medicine specialists and skilled anesthesiologists, reinforcing the notion that IVF should not be withheld as a treatment modality from patients with obesity.