Live birth outcomes in infertile patients with class III and class IV obesity following fresh embryo transfer

Assess the effect of class III (body mass index [BMI, kg/m²] 40-49.9) and class IV obesity (≥ 50) on clinical pregnancy and live birth outcomes after first oocyte retrieval and fresh embryo transfer cycle.

Cohort study SETTING: Academic center PATIENTS: Patients undergoing their first oocyte retrieval with planned fresh embryo transfer in our clinic between 01/01/2012 and 12/31/2018. Patients were stratified by BMI: 18.5-24.9 (n = 4913), 25-29.9 (n = 1566) 30-34.9 (n = 559), 35-39.9 (n = 218), and ≥ 40 (n = 114).

None MAIN OUTCOME MEASURE: Live birth rate RESULTS: Following embryo transfer, there were no differences in pregnancy rates across all BMI groups (p value, linear trend = 0.86). However among pregnant patients, as BMI increased, a significant trend of a decreased live birth rate was observed (p value, test for linear trend = 0.004). Additionally, as BMI increased, a significant trend of an increased miscarriage rate was observed (p value, linear trend = < 0.001). Compared to the normal-weight cohort, women with a BMI ≥ 40 had a significantly higher rate of cancelled fresh transfers after retrieval (18.4% vs. 8.2%, OR 2.51; 95%CI 1.55-4.08). Among singleton deliveries, a significant trend of an increased c-section rate was identified as the BMI increased (p value, linear trend = <0.001).

Overall, patients with a BMI > 40 have worse IVF treatment outcomes compared to normal-weight patients. After embryo transfer, their pregnancy rate is comparable to normal-weight women; however, their miscarriage rate is higher, leading to a lower live birth rate for pregnant women in this population. Patients with a BMI > 40 have a c-section rate that is 50% higher than normal-weight patients.