CHICAGO – Obesity was not associated with an increase in the risk of preterm birth among women with cerclage in a retrospective cohort study.
The rate of preterm births before 34 weeks’ gestation was similar in 103 nonobese women with cerclage and 93 obese women with cerclage (37.9% and 31.2%, respectively; odds ratio, 1.35) in a 2009-2011 study of patients, Dr. Lorene A. Temming and her colleagues reported in a poster at the annual meeting of the American Congress of Obstetricians and Gynecologists.
In fact, there were no differences in the rate of preterm births between the two groups at any of the other time points evaluated, including 24, 28, 32, and 37 weeks’ gestation, and there also was no difference in the rate of term births between the groups, according to Dr. Temming of Carolinas Medical Center, Charlotte, N.C., and her associates.
The nonobese patients had a body mass index less than 30 kg/m2, and the obese patients had a BMI of 30 or greater. The women all had singleton gestation, she noted.
The results of prior studies that investigated the effect of obesity on cerclage efficacy have conflicted. A secondary analysis of a large randomized trial of cerclage for short cervix showed no effect of obesity, but a smaller study showed that obesity was associated with increased risk of preterm birth prior to 35 weeks.
"Obesity increases risks of preeclampsia, gestational diabetes, and cesarean delivery, and is associated with increased operative morbidity with cesarean delivery. The role of obesity in preterm birth is less clear," Dr. Temming and her associates wrote.
Furthermore, although cerclage has been shown in multiple randomized, controlled trials and in a recent meta-analysis to reduce preterm birth in women with short cervical length, the effect of obesity on the efficacy of cerclage has also been unclear, they noted.
The current findings, which are derived from the second-largest data set available in the literature (although Dr. Temming listed sample size as a limiting factor in the study), are consistent with those from the larger of two prior studies, and suggest that obesity does not worsen outcomes in the setting of cerclage, she and her coauthors concluded.
Dr. Temming reported having no relevant financial disclosures.