Optimal blood pressure target to prevent severe hypertension in pregnancy: A systematic review and meta-analysis

Severe hypertension in pregnancy is a hypertensive crisis that requires urgent and intensive care due to its high maternal and fetal mortality. However, there is still a conflict of opinion on the recommendations of antihypertensive therapy. This study aimed to identify the optimal blood pressure (BP) levels to prevent severe hypertension in pregnant women with nonsevere hypertension. Ovid MEDLINE and the Cochrane Library were searched, and only randomized controlled trials (RCTs) were included if they compared the effects of antihypertensive drugs and placebo/no treatment or more intensive and less intensive BP-lowering treatments in nonsevere hypertensive pregnant patients. A random effects model meta-analysis was performed to estimate the pooled risk ratio (RR) for the outcomes. Forty RCTs with 6355 patients were included in the study. BP-lowering treatment significantly prevented severe hypertension (RR, 0.46; 95% CI, 0.37-0.56), preeclampsia (RR, 0.82; 95% CI, 0.69-0.98), severe preeclampsia (RR, 0.38; 95% CI, 0.17-0.84), placental abruption (RR, 0.52; 95% CI, 0.32-0.86), and preterm birth (< 37 weeks; RR, 0.81; 95% CI, 0.71-0.93), while the risk of small for gestational age infants was increased (RR, 1.25; 95% CI, 1.02-1.54). An achieved systolic blood pressure (SBP) of < 130 mmHg reduced the risk of severe hypertension to nearly one-third compared with an SBP of ≥ 140 mmHg, with a significant interaction of the BP levels achieved with BP-lowering therapy. There was no significant interaction between the subtypes of hypertensive disorders of pregnancy and BP-lowering treatment, except for placental abruption. BP-lowering treatment aimed at an SBP < 130 mmHg and accompanied by the careful monitoring of fetal growth might be recommended to prevent severe hypertension.