Impact of maternal obesity on preterm delivery in patients with cervical cerclage

BACKGROUND: Maternal obesity has risen in the United States in recent decades. OBJECTIVE: This study aimed to evaluate the impact of maternal obesity on the risk for spontaneous preterm delivery and the risk for overall preterm delivery among patients with cervical cerclage placement. STUDY DESIGN: This was a retrospective study in which data from the California Office of Statewide Health Planning and Development linked birth file from 2007 to 2012 were used, yielding a total of 3654 patients with and 2,804,671 patients without cervical cerclage placement. Exclusion criteria included patients with missing information on body mass index, multiple gestation, anomalous pregnancies, and gestations <20 weeks or >42 weeks. Patients in each group were identified and were further categorized based on body mass index with the nonobese group defined as having a body mass index of <30 kg/m(2), the obese group defined as having a body mass index of 30 to 40 kg/m(2), and the morbidly obese group defined as having a body mass index >40 kg/m(2). The risks for overall and spontaneous preterm delivery were compared between patients without obesity and those with obesity or those with morbid obesity patients. The analysis was stratified by cerclage placement. RESULTS: Among patients who underwent cerclage placement, the risk for spontaneous preterm delivery was not significantly different in the obese and morbidly obese group when compared with the nonobese group (24.2% vs 20.6%; adjusted odds ratio, 1.18; 95% confidence interval, 0.97–1.43; and 24.5% vs 20.6%; adjusted odds ratio, 1.12; 0.78–1.62, respectively). However, among patients without cerclage placement, the obese and morbidly obese groups had a higher risk for spontaneous preterm delivery than the nonobese group (5.1% vs 4.4%; adjusted odds ratio, 1.04; 1.02–1.05; and 5.9% vs 4.4%; adjusted odds ratio, 1.03; 1.00–1.07, respectively). The risks for overall preterm delivery at <37 weeks’ gestation were higher for the obese and morbidly obese groups than for the nonobese group among patients with cerclage (33.7% vs 28.2%; adjusted odds ratio, 1.23; 1.03–1.46; and 32.1% vs 28.2%; adjusted odds ratio, 1.01; 0.72–1.43, respectively). Similarly, among patients without cerclage placement, the risks for preterm delivery at <37 weeks’ gestation were higher for the obese and morbidly obese groups than for the nonobese group (7.9% vs 6.8%; adjusted odds ratio, 1.05; 1.04–1.06; and 9.3% vs 6.8%; adjusted odds ratio, 1.10; 1.08–1.13, respectively). CONCLUSION: Among patients who received a cervical cerclage for the prevention of preterm birth, obesity was not associated with an increased risk for spontaneous preterm delivery. However, it was associated with an overall increased risk for preterm delivery.