Women are at a greater risk of early death, particularly from cardiovascular diseases, if they develop a hypertensive disorder during pregnancy.
Experts say mothers should be monitored long-term, even if hypertension appears to resolve after birth.
Around one in 10 women globally develop a hypertensive disorder during pregnancy, such as chronic hypertension, preeclampsia, gestational hypertension and chronic hypertension with superimposed preeclampsia.
Research shows women who develop one of these conditions are three to five times more likely to develop chronic hypertension, but its effects on lifespan are unclear.
Now, an analysis of the health data from almost 90,000 women participating in the Nurses’ Health Study II between 1989 and 2017 suggests the effects are long-lasting.
Researchers found that one in seven women developed gestational hypertension or preeclampsia in one or more of their pregnancies.
And in the three-decade follow up period, they found those who developed gestational hypertension or preeclampsia during pregnancy had a 42% greater risk of dying before age 70 than those who didn’t.
In particular, these women were more than twice as likely to die of cardiovascular disease than those who didn’t develop hypertensive disorders during pregnancy.
These links remained, even if women did not report persistent hypertension after birth.
“Our results highlight the need for clinicians to screen for the history of hypertensive disorders in pregnancy when evaluating CVD morbidity and mortality risk of their patients,” study author Associate Professor Jorge E. Chavarro, of the Harvard T.H. Chan School of Public, said.
Professor Thomas Marwick, director of the Baker Heart and Diabetes Institute, said the study reinforced a trend that his group had been studying: that anyone who developed pregnancy-related hypertension should be followed carefully afterwards.
Nevertheless, this epidemiological study wasn’t enough to confirm that the link was causal, in that factors underpinning pregnancy-related hypertension such as being overweight or gaining weight during pregnancy could be an independent driver in both, he said.
The study itself found women who developed a hypertensive disorder were more likely to have a higher BMI at baseline, gestational diabetes, parental history of diabetes and MI/stroke and chronic hypertension.
It could also be that these women had undiagnosed hypertension that was not reported to the researchers, he added.
“It could be that the pregnancy-associated hypertension is a marker of risk rather than a cause,” Professor Marwick said.
This study was one of a number now pointing to the link, suggesting a need for guidelines to boost awareness among clinicians, he said.
The authors provided some possible biological mechanisms for the discovered link. For example, insulin resistance and systemic inflammation were both risk factors for CVD and hypertension disorders in pregnancy.
“In addition, the pathological processes implicated in hypertensive disorders in pregnancy, including angiogenic imbalance, complement activation, inflammation, and hemodynamic changes, may also contribute directly to cardiac stress that exceeds normal pregnancy, leading to overt cardiac damage,” they wrote.
“Finally, the association between hypertensive disorders in pregnancy and CVD may also be mediated by epigenomic changes,” they added, pointing to research identified differentially methylated regions predisposing the offspring of women with hypertensive disorders in pregnancy to later-life vascular diseases.
“There is also evidence showing that these mentioned pathways are involved in the associations between HDPs and other chronic diseases,” the authors said.
The study authors also found pregnancy-related hypertension was linked to a greater likelihood of death due to non-cardiovascular reasons too, including infectious diseases, respiratory diseases, nervous system diseases, and metabolic/immunity disorders.
“Contemporary management of women with HDPs will need better risk assessment tools informed by precision medicine to appropriately identify those women who are at greatest risk of premature CVD and to develop algorithms for early intervention in order to change the trajectory of these women,” wrote the author of the linked editorial, Assistant Professor Garima Sharma at the Johns Hopkins University School of Medicine.