346: Disparate rates of cesarean delivery in term nulliparous women with hypertensive disorders of pregnancy

Abstract

Despite the evidence supporting the safety of vaginal delivery in the setting of hypertensive disorders of pregnancy, women with this diagnosis continue to have high cesarean delivery (CD) rates. The aim of this study was to evaluate whether the increased CD rate in women with hypertensive disorders of pregnancy could be explained by maternal, sociodemographic, or obstetric comorbidities, or whether other external factors may be driving this phenomenon. This is a retrospective cohort study of nulliparous, term, singleton, vertex (NTSV) women delivering at 37 to 42 weeks using the US National Vital Statistics Report dataset for the year 2013. We compared prevalence of maternal, sociodemographic, and potential comorbid obstetric conditions that increase risk for CD between women diagnosed with hypertensive disorders of pregnancy and those without the diagnosis. We then used multivariate logistic regression to control for these risk factors and calculated adjusted probabilities of CD for women with and without a diagnosis of hypertensive disorders of pregnancy. We analyzed 1,439,977 NTSV women, 5% of whom were diagnosed with hypertensive disorders of pregnancy. The subgroup with hypertensive disorders of pregnancy had more risk factors for CD, most notably morbid obesity (9.0% versus 3.1%, p<0.01), diabetes (9.9% versus 4.4%, p<0.01), and induction of labor (59.2 versus 26.9%, p<0.01). The unadjusted probability of CD in women with hypertensive disorders of pregnancy was 39.5% versus 26.8% in those without the diagnosis (p<0.01; Table). After controlling for these risk factors, women with hypertensive disorders of pregnancy were significantly more likely to undergo CD than those without hypertensive disorders of pregnancy (35.1% versus 26.4%; aOR 1.53 [1.50-1.56], p<0.01). After controlling for other risk factors, the diagnosis of hypertensive disorders of pregnancy remained a significant risk factor for primary CD in NTSV women, suggesting a widespread and concerning management practice that is not supported by the most recent clinical evidence. Women with hypertensive disorders of pregnancy may therefore represent an important target population in ongoing efforts aimed at reduction of primary CD rates.