Maternal hypertensive disorders of pregnancy and electrocardiographic findings among newborns: The Copenhagen Baby Heart Study.

Background: Maternal preeclampsia is associated with both congenital heart defects and changes in left ventricular structure and function in the offspring. Whether preeclampsia and gestational hypertension also affect the offspring's cardiac conduction system is unknown.

Objectives: This study assesses whether infants exposed to maternal hypertensive disorders of pregnancy (HDPs) exhibit changes in their electrocardiogram (ECG) compared with infants unexposed to HDPs.

Methods: This population-based cohort study included newborns from the Copenhagen Baby Heart Study who had an ECG performed within 30 days of birth and had available obstetric information. ECG parameters of newborns exposed to maternal HDPs were compared with those of unexposed newborns using linear regression.

Results: Our study cohort included 11,826 newborns, including 441 exposed to maternal preeclampsia and 320 exposed to gestational hypertension. Infants exposed to preeclampsia had prolonged QRS durations (adjusted mean difference 0.6 ms, 95% confidence interval [CI] 0.04, 1.16) and lower maximum amplitudes of the R-wave in V1 (adjusted mean difference, linear scale 0.95, 95% CI 0.90, 1.00), compared with unexposed infants. Exposure to maternal preeclampsia was not associated with changes in other ECG parameters. Exposure to gestational hypertension was associated with increased QT interval durations (QT_c Bazett, adjusted mean difference 2.48 ms, 95% CI -0.23, 5.20; QT_c Fridericia, adjusted mean difference 2.32 ms, 95% CI -0.19, 4.83).

Conclusions: Our findings suggest that the newborn cardiac conduction system is affected by exposure to maternal preeclampsia. This could reflect the previously described thickening of the left ventricular myocardium in infants exposed to preeclampsia.