Fetal Myelomeningocele Closure in the Setting of Maternal Body Mass Index 35 to 40

Background and objectives: The Management of Myelomeningocele Study established a role for maternal-fetal surgery for myelomeningocele (MMC) but was limited to patients with a maternal body mass index (BMI) less than 35 kg/m2. However, as the rate of obesity has increased globally, some centers have extended the Management of Myelomeningocele Study criteria to include patients with a BMI of 35 to 40 kg/m2. We used the Fetal MMC Consortium registry to analyze the complications associated with maternal-fetal surgery in patients with a maternal BMI < 35 kg/m2 compared with 35 to 40 kg/m2. Methods: The prospective observational Fetal MMC Consortium registry sponsored by the North American Fetal Therapy Network was used to extract deidentified "maternal complication" and "fetal/neonatal complication" data sets, corresponding to patients with complete entries related to maternal or fetal/neonatal complications, respectively. Demographics, clinical characteristics, and complications were recorded. Propensity score matching was conducted with a 2:1 algorithm, and outcomes were compared between patients with BMI < 35 kg/m2 and those with BMI 35 to 40 kg/m2. Results: Propensity score matching resulted in 156 patients with BMI < 35 kg/m2 and 78 patients with BMI 35 to 40 kg/m2 in the "maternal complication" data set, and 130 patients with BMI < 35 kg/m2 and 65 patients with BMI 35 to 40 kg/m2 in the "fetal/neonatal complication" data set. No significant differences in the median number of maternal (2.0 vs 2.0; P = .257) or median number of fetal/neonatal (1.0 vs 1.0; P = .409) complications were observed between the 2 cohorts. Furthermore, prematurity rates did not differ significantly between the BMI < 35 and BMI 35 to 40 cohorts. Conclusion: Maternal-fetal surgery for open neural tube defect closure is not associated with increased risks among patients with a maternal BMI of 35 to 40 kg/m2. Extending the initial inclusion criteria for prenatal MMC closure has the potential to expand access to patients with a higher risk for open neural tube defects.