The Management of Myelomeningocele Study: obstetrical outcomes and risk factors for obstetrical complications following prenatal surgery.

BACKGROUND: The Management of Myelomeningocele Study was a multicenter randomized trial to compare prenatal and standard postnatal closure of myelomeningocele. The trial was stopped early at recommendation of the data and safety monitoring committee and outcome data for 158 of the 183 randomized women published.

OBJECTIVE: In this report, pregnancy outcomes for the complete trial cohort are presented. We also sought to analyze risk factors for adverse pregnancy outcome among those women who underwent prenatal myelomeningocele repair.

STUDY DESIGN: Pregnancy outcomes were compared between the 2 surgery groups. For women who underwent prenatal surgery, antecedent demographic, surgical, and pregnancy complication risk factors were evaluated for the following outcomes: premature spontaneous membrane rupture ≤34 weeks 0 days (preterm premature rupture of membranes), spontaneous membrane rupture at any gestational age, preterm delivery at ≤34 weeks 0 days, nonintact hysterotomy (minimal uterine wall tissue between fetal membranes and uterine serosa, or partial or complete dehiscence at delivery), and chorioamniotic membrane separation. Risk factors were evaluated using χ2 and Wilcoxon tests and multivariable logistic regression.

RESULTS: A total of 183 women were randomized: 91 to prenatal and 92 to postnatal surgery groups. Analysis of the complete cohort confirmed initial findings: that prenatal surgery was associated with an increased risk for membrane separation, oligohydramnios, spontaneous membrane rupture, spontaneous onset of labor, and earlier gestational age at birth. In multivariable logistic regression of the prenatal surgery group adjusting for clinical center, earlier gestational age at surgery and chorioamniotic membrane separation were associated with increased risk of spontaneous membrane rupture (odds ratio, 1.49; 95% confidence interval, 1.01-2.22; and odds ratio, 2.96, 95% confidence interval, 1.05-8.35, respectively). Oligohydramnios was associated with an increased risk of subsequent preterm delivery (odds ratio, 9.21; 95% confidence interval, 2.19-38.78). Nulliparity was a risk factor for nonintact hysterotomy (odds ratio, 3.68; 95% confidence interval, 1.35-10.05).

CONCLUSION: Despite the confirmed benefits of prenatal surgery, considerable maternal and fetal risk exists compared with postnatal repair. Early gestational age at surgery and development of chorioamniotic membrane separation are risk factors for ruptured membranes. Oligohydramnios is a risk factor for preterm delivery and nulliparity is a risk factor for nonintact hysterotomy at delivery.