Fall in mean arterial pressure and fetal growth restriction in pregnancy hypertension: a meta-analysis

Background We investigated the relation between fetoplacental growth and the use of oral antihypertensive medication to treat mild-to-moderate pregnancy hypertension. Methods The study design was a metaregression analysis of published data from randomised controlled trials. Data from a paper that was regarded as an extreme statistical outliner were excluded from primary analyses. The change in (group) mean arterial pressure (MAP) from enrolment to delivery was compared with indicators of fetoplacental growth. Findings Greater mean difference in MAP with antihypertensive therapy was associated with the birth of a higher proportion of small-for-gestational-age (SGA) infants (slope: 0.09 [SD 0.03], r(2)=0.48, p=0.006, 14 trials) and lower mean birthweight significant after exclusion of data from another paper regarded as an extreme statistical outliner (slope: -14.49 [6.98] r(2)=0.16, p=0.049, 27). No relation with mean placental weight was seen (slope -2.01 [1.62], r(2)=0.15, p=0.25, 11 trials). Interpretation Treatment-induced falls in maternal blood pressure may adversely affect fetal growth. Given the small maternal benefits that are likely to be derived from therapy, new data are urgently needed to elucidate the relative maternal and fetal benefits and risks of oral antihypertensive drug treatment of mild-to-moderate pregnancy hypertension.