Management of non-severe pregnancy hypertension – A summary of the CHIPS Trial (Control of Hypertension in Pregnancy Study) research publications

The international CHIPS Trial (Control of Hypertension In Pregnancy Study) enrolled 987 women with chronic (75%) or gestational (25%) hypertension. Pre-eclampsia developed in 48%; women remained on their allocated BP control and delivered an average of two weeks later. 'Less tight' control (target diastolic BP 100 mmHg) achieved BP that was 6/5mmHg higher (p < 0.001) than 'tight' control (target diastolic 85 mmHg, BP achieved 133/85 mmHg). 'Less tight' (vs. 'tight') control resulted in similar adverse perinatal outcomes (31.5% vs. 30.7%; p = 0.84) that balanced birthweight < 10th percentile (16.1% vs. 19.8%; p = 0.14) against preterm birth (35.6% vs. 31.5%; p = 0.18). 12-month follow-up revealed no compelling evidence for developmental programming of child growth. However, 'less tight' (vs. 'tight') control resulted in more severe maternal hypertension (40.6% vs. 27.5%; p < 0.001), and more women with platelets < 100 × 10⁹/L (4.3% vs. 1.6%; p = 0.02) or symptomatic elevated liver enzymes (4.3% vs. 1.8%; p = 0.03), with no difference in serious maternal complications (3.7% vs. 2.0%; p = 0.17). Labetalol was the drug of choice. Methyldopa did not result in inferior outcomes. Post-hoc, severe hypertension, independent of pre-eclampsia, was associated with heightened increased risk of adverse outcomes, and in 'less tight' control, of serious maternal complications. At no gestational age at initiation of BP control was 'less tight' superior to 'tight'. Women in both groups were equally satisfied with care. 'Less tight' control tended to be more expensive by CAD$6000 (p =0.07) based on neonatal care costs. Collectively, CHIPS publications have provided evidence that women with non-severe pregnancy hypertension should receive 'tight' BP control achieved by a simple algorithm.