Less-Tight versus Tight Control of Hypertension in Pregnancy

The Authors Reply: CHIPS showed that lesstight control was not superior to tight control for the baby but was associated with more severe hypertension for the mother.Given the similarity of the blood pressure control interventions in the Chronic Hypertension and Pregnancy (CHAP) project (ClinicalTrials.govnumber, NCT02299414) and CHIPS, we analyzed outcome data according to the CHAP project protocol for the 736 women with chronic hypertension who were enrolled in CHIPS.The CHAP project has two primary outcomes.The group randomly assigned to lesstight (vs.tight) control had a higher incidence of the first primary outcome, a composite adverse maternal and perinatal outcome (42.8% vs. 32.1%;adjusted odds ratio, 1.54; 95% CI, 1.13 to 2.10), and a lower incidence of the second primary outcome, small-for-gestational-age infants (13.9% vs. 19.7%;adjusted odds ratio, 0.66; 95% CI, 0.45 to 0.99).Other findings suggest that any favorable effect of less-tight (vs.tight) control on fetal growth is unlikely to be clinically important.As noted in our article, the groups did not differ significantly with respect to the primary prespecified outcome of our trial (pregnancy loss or high-level neonatal care for >48 hours).We found no benefit in additional analyses assessing adverse secondary outcomes prespecified in the CHAP project for the baby (severe adverse perinatal outcome, 8.7% in the less-tight-control group vs. 5.8% in the tight-control group; adjusted odds ratio, 1.68; 95% CI, 0.94 to 3.03) or for the mother (see Table S1 in the Supplementary Appendix, available with the full text of this letter at NEJM.org).Our finding that less-tight control was associated with more severe hypertension persisted after adjustment for the higher prevalence of severe hypertension among women randomly assigned to less-tight control.We would caution against regarding progression to severe hypertension as something that "can be identified and treated"; failure to identify and treat it has been recognized in reviews of maternal deaths as the single most important failing in the care of women with pregnancy hypertension. 1