Pre-existing hypertension in pregnancy

Hypertension is common during pregnancy, complicating ∼10–15% of all pregnancies in the UK. The number of women who enter pregnancy affected by chronic hypertension is less clear, but has been estimated at ∼3%. Risk factors for chronic hypertension include maternal race and ethnicity, age, and body mass index (BMI). The changing demographics of today's antenatal population mean that pre-existing hypertension in pregnancy is an increasing clinical problem. Chronic hypertension in pregnancy can be defined as hypertension known to be present prior to conception or first recognised before 20 weeks of gestation. Patients with chronic hypertension are at risk of a variety of adverse maternal and fetal outcomes, and hence should have a comprehensive plan of care. Optimal care includes pre-conceptual counselling, frequent antenatal visits during pregnancy, timely delivery, appropriate intrapartum monitoring, and postpartum follow up. The relative risk of superimposed pre-eclampsia in women with chronic hypertension is nearly eightfold higher than in the general population, and all adverse neonatal outcomes are at least twice as likely to occur compared to the general population.