292. Risk factors for superimposed preeclampsia in women with chronic hypertension

Abstract

Introduction Chronic maternal hypertension is associated with a 3 to 5-fold increased risk of preeclamspia. The compounding effect of additional risk factors on both preeclampsia risk and pregnancy outcome in such patients is uncertain. Objectives/hypothesis We hypothesised there may be additional risk factors identifiable in early pregnancy within this cohort which are associated with an increased risk of preeclampsia. If so, early risk stratification may help guide management and intervention to attenuate this risk. Methods Risk factors for preeclampsia identified at the pregnancy booking visit in women with known chronic hypertension were obtained from two centres in Melbourne, Australia in a retrospective analysis of 42,500 singleton deliveries(2008–2018). Risk factors included age, parity, previous preeclampsia, ethnicity, smoking, secondary hypertension, renal disease/proteinuria, hypertension duration, diabetes, antihypertensive use at conception and/or first trimester, aspirin use before 16 weeks, blood pressure(BP) at booking and body mass index(BMI). Associations were evaluated by univariate and multivariate logistic regression analysis, with significance p Results 233 births occurred in women with chronic hypertension(0.55% prevalence). Preeclampsia occurred in 36(15.5%) of these births, of which 19(8.2%) were severe preeclampsia. On univariate analysis, previous preeclampsia [OR 5.45(1.89–12.71)] and hypertension duration [OR 2.4(1.76–4.92)] were most strongly associated with any severity of preeclampsia. Adjusting for age, parity, previous preeclampsia, BMI, BP and renal disease, hypertension duration > 5 years remained an independent risk factor [OR 1.23(1.03–1.48)]. For severe preeclampsia, strongest associations were maternal age > 35, renal disease, BMI Discussion Risk of preeclampsia of any severity and severe preeclampsia were most strongly associated with a duration of hypertension > 5 years and previous preeclampsia respectively. This highlights the importance of careful clinical appraisal in early pregnancy in women with chronic hypertension as early interventions (eg. aspirin) may mitigate risk of preeclampsia in this group.