Abstract

OBJECTIVES: This study aimed to assess the impact of maternal ethnicity on the risk of adverse perinatal outcome in pregnant women with chronic hypertension. METHODS: Demographic and delivery data of women with chronic hypertension and singleton pregnancies from three obstetric units (2000 to 2014) were collated. Multivariable logistic regression models were used to calculate risk ratios (RR) by ethnic group for adverse perinatal outcome in women with chronic hypertension adjusted for other maternal characteristics. The impact of maternal ethnicity on birthweight centile calculation was investigated by comparing customised birthweight centile (GROW) to birthweight centile calculator that does not adjust for maternal ethnicity (Intergrowth 21st ). RESULTS: The cohort included 4045 women (4481 pregnancies) with chronic hypertension. Women of White ethnicity accounted for 47% (n=2122) of the cohort; 36% were Black (n=1601) and 8.5% Asian (n=379). The overall incidence of stillbirth was 1.6%, preterm birth <37 weeks 16%, and fetal growth restriction (birthweight <3rd centile) 11%. Black women, compared to White women, had the highest risk for all adverse perinatal outcomes: stillbirth 3.1% versus 0.6% (adjusted RR 5.56; 95% CI 2.79 to 11.09), preterm birth <37 weeks 21% versus 11% (aRR 1.70; 95% CI 1.43 to 2.01), birthweight <3rd centile 16% versus 7.4% (aRR 2.07; 95% CI 1.71 to 2.51). Asian women, compared to White women, were also at increased risk of adverse perinatal outcomes: stillbirth 1.6% versus 0.6% (aRR 3.03; 95% CI 1.11 to 8.28), preterm birth <37 weeks 20% versus 11% (aRR 1.86; 95% CI 1.44 to 2.40) and birthweight <3rd centile 12% versus 7.4% (aRR 1.69; 95% CI 1.24 to 2.30). CONCLUSIONS: Black ethnicity (compared to White) is associated with the greatest risk of adverse perinatal outcome in women with chronic hypertension even after adjusting for other maternal characteristics. Women of Asian ethnicity are also at increased risk, but to a lesser extent. This article is protected by copyright. All rights reserved.