PERINATAL MORBIDITY IN CHRONIC HYPERTENSION

Objective To investigate if chronic hypertension in the absence of sup erimposed pre-eclampsia is associated with increased perinatal morbidi ty (especially small for gestational age babies and preterm deliveries ) when compared to the general obstetric population. Design A retrospe ctive cohort study. Setting A tertiary referral obstetric hospital. Pa rticipants One hundred and fifty-five pregnant women with chronic hype rtension who had a diastolic blood pressure of greater than 90 mmHg be fore 20 weeks or had pre-existing essential hypertension were studied. The study period was January 1 1991 to June 30 1993. Main outcome mea sures Perinatal related loss rate, birthweight less than the fifth cen tile (small for gestational age) preterm delivery, placental abruption and development of superimposed preeclampsia. Results Women with chro nic hypertension without superimposed pre-eclampsia had an increased r ate of small for gestational age babies (10.9 %) compared with the gen eral population (4.1 %) (odds ratio 2.9 [confidence interval 1.6 to 5. 0]). Women with chronic hypertension without superimposed pre-eclampsi a did not have a significant increase in preterm delivery or perinatal loss. Severe hypertension (diastolic blood pressure greater than or e qual to 110) at less than 20 weeks was associated with a trend to an i ncreased risk of small for gestational age babies (odds ratio 3.8 [con fidence interval 1.0 to 13.7]), increased rate of delivery at less tha n 32 weeks (odds ratio 7.4 [confidence interval 1.9 to 29.5]) and incr eased rate of superimposed pre-eclampsia (odds ratio 5.2 [confidence i nterval 1.5 to 17.2]). Women with superimposed pre-eclampsia had the g reatest perinatal morbidity. Conclusions Women with chronic hypertensi on without pre-eclampsia have an increased risk of delivering a small for gestational age baby. Perinatal morbidity and pre-eclampsia is gre atest in women with severe hypertension at less than 20 weeks. Preterm delivery is more common in women with superimposed pre-eclampsia.