Chronic hypertension adversely affects pregnancy outcomes

Pregnant women with chronic hypertension are more likely to have unfavourable maternal, foetal, and neonatal outcomes compared with their normotensive counterparts, according to the results of a meta-analysis. Furthermore, exposure to blood-pressure (BP) lowering treatment may contribute to a higher risk of small for gestational age (SGA).

The current systematic review and meta‐analysis pooled data from 94 studies, of which 81 assessed the effect of chronic hypertension while 16 examined that of antihypertensive treatment. Funnel plots and Egger’s test indicated no significant publication bias. The total scores for studies' quality according to Newcastle‐Ottawa grading ranged from 4 to 9, with poorer quality among studies examining the effect of BP lowering.

Chronic hypertension was associated with increased likelihood of pre-eclampsia (adjusted odd ratio [aOR], 5.43, 95 percent confidence interval [CI], 3.85–7.65), caesarean section (aOR, 1.87, 95 percent CI, 1.6–2.16), maternal mortality (aOR, 4.80, 95 percent CI, 3.04–7.58), preterm birth (aOR, 2.23, 95 percent CI, 1.96–2.53), stillbirth (aOR, 2.32, 95 percent CI, 2.22–2.42), and SGA (aOR, 1.96, 95 percent CI, 1.6–2.40). The associations persisted even after controlling for maternal race/ethnicity in subgroup analyses.

Meanwhile, women with chronic hypertension on antihypertensive treatment had higher odds of SGA compared with those who received no treatment (aOR, 1.86, 95 percent CI, 1.38–2.50).

More studies are needed to establish whether the association between BP-lowering therapy and SGA is a direct effect of the treatment or because severe hypertension during pregnancy is a risk factor for SGA and women with severe hypertension are more likely to be treated.