Baby's birthweight increases risk of cardiovascular disease in preeclamptic and hypertensive women

A new study shows that preeclamptic and hypertensive pregnant women's risk of getting cardiovascular disease is linked to their baby's birthweight.

Preeclampsia and other hypertensive disorders of pregnancy (HDPs) are serious pregnancy complications that can be dangerous for both mother and baby.

These conditions are associated with higher risk of preterm delivery and smaller infant size for gestational age, leaving babies born of preeclamptic pregnancies needing more care after birth for the best chance of a healthy life.

For mothers, HDPs are characterized by high blood pressure during pregnancy, and can lead to deadly complications in the brain and liver. Even years after birth, women who had preeclampsia are at higher risk of high blood pressure, stroke, and heart attack

Researchers have assumed until now that HDPs which are more dangerous for the baby are also more dangerous for the mother.

That is, that the more "severe" preeclampsia cases where the baby is born too early and too small are associated with higher risk of cardiovascular disease (CVD) long term for the mother.

This assumption is logical because preterm delivery and small infant size are independently associated with maternal CVD risk."

Sage Wyatt, Ph.D. candidate at the Faculty of Medicine, University of Bergen, Norway

Recently, however, she has published a paper in international journal Pediatric and Perinatal Epidemiology that challenges this assumption.

The bigger the baby, the bigger the risk

In this paper, Wyatt investigated risk of death due to stroke, heart attack, and peripheral arterial disease in Norwegian mothers.

She and her colleagues examined differences in this risk of death by mother's history of HDP, preterm birth, and infant size in their first pregnancy.

What makes this study different from previous studies is that in addition to studying women with smaller infants, they also examined the risk of mothers with larger infants.

"Mothers with preterm HDP, in fact, appeared to have opposite trends in CVD by infant birthweight by gestational age than any other group", Wyatt explains, and elaborates:

"Mothers with term delivery or normotensive preterm in their first pregnancy had decreasing risk of CVD death with increasing infant size. The exception was mothers with preterm HDP, who instead had the highest risk with an above average size infant."

Notably, Wyatt adds, "this risk is not confined to mothers with extremely large infants, but rather appears to increase gradually, starting from below the mean."

Could be explained by other underlying cardiometabolic risk factors

This finding has been overlooked in much of the previous literature, and it is still not well understood what explains this surprising relationship with birthweight.

"Mothers with large for gestational age infants often have underlying cardiometabolic risk factors such as gestational diabetes or obesity, making a higher risk of CVD plausible," Wyatt suggests:

"Further research into this topic could tell us more about the underlying mechanisms behind HDP, which remain unclear."