Mean arterial pressure elevation linked to adverse neonatal outcomes

Elevated mean arterial pressure during pregnancy poses an increased risk of adverse neonatal outcomes, except necrotizing enterocolitis (NEC), according to the secondary analysis of the Chronic Hypertension and Pregnancy (CHAP) trial.

The analysis included 2,284 participants with mild chronic hypertension (blood pressure [BP] 140–159/90–104 mm Hg) and singleton pregnancies <23 weeks of gestation. These participants were randomly assigned to receive active treatment (maintained on antihypertensive therapy with a goal BP <140/90 mm Hg; n=1,155) or standard treatment (control; antihypertensives withheld unless BP reached ≥160 mm Hg systolic BP or ≥105 mm Hg diastolic BP; n=1,129).

Logistic regression was used to examine the association between mean arterial pressure (average and highest across study visits) and the primary neonatal composite outcome (ie, bronchopulmonary dysplasia, retinopathy of prematurity, NEC, or intraventricular haemorrhage grade 3 or 4) and individual secondary outcomes (neonatal intensive care unit admission [NICU], low birth weight [LBW] <2,500 g, and small for gestational age [SGA]).

Increasing average mean arterial pressure per millimeter of mercury was associated with an increase in each neonatal outcome examined except NEC. The corresponding adjusted odds ratios were 1.12 (95 percent confidence interval [CI], 1.09–1.16) for the neonatal composite outcome, 1.07 (95 percent CI, 1.06–1.08) for NICU admission, 1.12 (95 percent CI, 1.11–1.14) for LBW, 1.03 (95 percent CI, 1.01–1.06) for SGA below the fifth percentile, and 1.02 (95 percent CI, 1.01–1.04) for SGA below the 10th percentile.

Models using the highest mean arterial pressure versus the average mean arterial pressure also yielded similar associations.