Effect of very preterm delivery on outcomes following in utero spina bifida repair.

Objective: In utero fetal spina bifida repair decreases the risk for cerebrospinal fluid (CSF) diversion including ventriculoperitoneal (VP) shunt placement, reverses hindbrain herniation, and improves motor function with a higher likelihood of independent ambulation. Unfortunately, in utero surgery can be complicated by preterm delivery. The goal of this study was to compare pregnancy and neonatal outcomes between individuals who delivered very preterm, and those who delivered later in gestation following in-utero spina bifida repair. Methods: Data from the North American Fetal Therapy Network (NAFTNet) Fetal Myelomeningocele Consortium (fMMC) registry collected from 2011 to 2024 were analyzed. Three cohorts of patients were categorized by gestational age at delivery and compared: <30 weeks, 30-34 weeks, and >34 weeks. Comparisons between groups for maternal and delivery outcomes were completed for the entire cohort and then analyzed for those with available CSF diversion data up to one year of life. Chi-square or Fisher's exact tests were used to compare categorical variables, and Kruskal-Wallis tests were used to determine if there are significant differences between the distributions of the three groups. A p-value <0.05 was considered significant. Results: A total of 1,213 patients were analyzed (<30-weeks n = 111 [9.2%], 30-34 weeks n = 323 [26.6%], >34-weeks n = 779 [64.2%]). Overall fetal and neonatal mortality was 2.2%, 85% of which occurred in the <30 weeks cohort, where perinatal mortality was 21%. Latency from fetal surgery to delivery averaged 2.1 weeks for the <30 weeks group. Rates of abruption, chorioamnionitis, and spontaneous labor were higher in the <30 week group compared to later gestational age cohorts. Neonatal morbidity was also significantly higher in the <30 weeks cohort for sepsis, apnea, respiratory distress, patent ductus arteriosus, intraventricular hemorrhage and periventricular leukomalacia in the <30 weeks cohort. CSF diversion data was available for 677 neonates (<30 weeks n = 53, 30-34 weeks n = 186, >34 weeks n = 438). There was no significant difference in VP shunt placement between the different gestational age groups. Conclusion: Very preterm birth following in utero spina bifida repair results in significant perinatal mortality and neonatal morbidity. Delivery prior to 30 weeks of gestation occurs in 9% of patients after in utero spina bifida repair, resulting in a 21% perinatal mortality rate. However, even among those who delivered very preterm, a reduction in VP shunt rates, a benefit of in utero repair, appears to be preserved. Further data are warranted to assess the impact of prematurity following in-utero surgery on ambulation and developmental outcomes.