Objective: This study was performed to evaluate the effect of pre-pregnancy body mass index (BMI) on the success of cerclage.
Materials and methods: A retrospective cohort study of women who had a history-indicated (HIC) or ultrasound-indicated cerclage (UIC) placed between 1994 and 2011. Based on pre-pregnancy BMI (World Health Organization criteria), three cohorts were defined: normal/overweight (BMI: 20.0-29.9 kg/m(2)), obese class I/II (BMI: 30.0-39.9 kg/m(2)) and obese class III (BMI ≥ 40.0 kg/m(2)). The primary outcome was spontaneous preterm birth (sPTB) <35 weeks. The secondary outcomes included but were not limited to gestational age of delivery, sPTB <37, <32 and <28 weeks, preterm premature rupture of membranes and birth weight.
Results: 375 women were included for analysis. Demographics were similar in the three BMI categories, except black race (p = 0.01). The rates of sPTB <35 weeks were similar between each cohort: 24.3%, 23.0% and 27.7%, respectively (p = 0.81). BMI was not a predictor of any of the secondary outcomes. A HIC was placed in 47.2% and an UIC was placed in 52.8% women. Both unadjusted and adjusted analysis showed no significant difference in sPTB <35 weeks between BMI categories overall or by cerclage type (HIC or UIC).
Conclusions: Pre-pregnancy BMI is not a significant predictor of sPTB <35 weeks in women with HIC or UIC.
Keywords: Body mass index; cervical cerclage; history-indicated cerclage; preterm birth; ultrasound-indicated cerclage.