Elevated preconception blood pressure linked to adverse pregnancy outcomes

Expectant mothers with high blood pressure (BP) levels before pregnancy are at increased risk of adverse pregnancy outcomes, as reported in a study.

Researchers used data from the National Free Preconception Checkup Project in Guangdong Province, China. They included a total of 567,127 mother-neonate-father triads in the analysis.

The American College of Obstetricians and Gynecologists definition of hypertension was used to categorize maternal BP levels within 1 year before pregnancy. The primary outcome was a composite of adverse pregnancy outcomes, including preterm birth, small for gestational age, and perinatal infant death.

Log-binomial and marginal structural binomial regressions showed that the risk of a composite of adverse pregnancy outcomes relative to women with normal BP were higher among women with elevated BP (adjusted risk ratio [RR], 1.07, 95 percent confidence interval [CI], 1.05–1.09; absolute risk difference, 1.03 percent 95 percent CI, 0.72–1.29) or hypertension (adjusted RR, 1.25, 95 percent CI, 1.18–1.32; and absolute risk difference, 3.42 percent, 95 percent CI, 1.97–5.42).

The risk increase was observed for multiple adverse pregnancy outcomes, preterm birth, small for gestational age, and perinatal infant death. However, the strength of these associations decreased with increasing duration of pregnancy preparation, with the significance disappearing beyond 90 days of pregnancy preparation.

The findings highlight the importance of preconception hypertension screening and control among women.