749 Performance of cervical length screening in obese women

Abstract

Universal cervical length (CL) screening is recommended in all singleton pregnancies to identify patients at risk of spontaneous preterm birth (sPTB) with treatments available to decrease this risk. Since the prevalence of obesity in pregnancy is rising, we aimed to characterize midtrimester CL and evaluate the association of CL and sPTB in nulliparous obese women. This is a retrospective cohort study of 5502 nulliparous women undergoing universal transvaginal CL screening at 17-23 weeks gestation age between 2011-2016. Women with CL ≤20mm were offered intervention for short cervix. The distribution of cervical length in obese (BMI ≥30) women was plotted. The incidence of CL ≤15mm, ≤20mm, and ≤25mm was compared between obese and nonobese women. The rate of preterm birth was compared between the two groups. Receiver operating characteristic curves were used to compare the performance of CL screening in prediction of sPTB <34 weeks. Of the 5502 patients in the cohort, 1427 (25.9%) were obese. Although the mean cervical length increased with increasing BMI class (nonobese 39.9 + 6.9mm, class 1 obesity 40.9 + 7.0mm, class 2 obesity 41.1 + 7.8mm, class 3 obesity 40.0 + 7.6mm, p <0.01), obese and nonobese women had similar rates of short cervix at all examined cutoffs. Compared to nonobese patients, obese patients had a higher likelihood of sPTB prior to 34, 28, and 24 weeks. The rate of sPTB <37 weeks was similar between obese and nonobese women (Table) and occurred in 50% of patients with CL <20mm in both groups. CL performed equally well as a predictor for sPTB <34 weeks in obese and nonobese women (Figure). The sensitivity and specificity of CL <20mm for sPTB <34 weeks did not differ between groups. Obese women are at higher risk for sPTB prior to 34, 28, and 24 weeks. This risk appears to be independent of midtrimester CL, suggesting that the etiology of PTB in obese patients may not be cervical insufficiency.View Large Image Figure ViewerDownload Hi-res image Download (PPT)