Women who develop transient hypertensive disorders during their pregnancy are at risk for developing subsequent cardiovascular disease (CVD), particularly if this experienced at the same time as gestational diabetes.
In a large population-based study, the adjusted hazard ratios for developing CVD following a gestational hypertensive disorder (GHTD) alone were 1.90 (95% confidence interval, 1.151-2.25) within 5 years and 1.41 (95% CI, 1.12-1.76) after 5 years or more.
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When gestational diabetes was added into the mix, however, the risk for CVD after 5 years more than doubled (aHR, 2.43; 95% CI, 1.60-3.67). Risk in the earlier postpartum period was also raised by the combination, but this was not significant (aHR, 1.42; 95% CI, 0.78-2.58).
Having gestational diabetes by itself did not seem to increase the risk for later CVD in the analysis, despite being linked to higher heart disease risk in other studies.
“These are women coming out of a pregnancy – young women of reproductive age – so this is not a group that typically has cardiovascular events,” said Ravi Retnakaran, MD, in an interview, an investigator in the new study, which is published in JAMA Network Open.
“If they are somebody who has both disorders concurrently in their pregnancy, they may be at even greater risk than a woman with one or the other disorder,” added Dr. Retnakaran, who is professor of medicine at the University of Toronto and an endocrinologist at the Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, also in Toronto. “In other words, amongst already high-risk patients. This is identifying a subset at maybe an even higher risk.”
It doesn’t mean that there is a huge absolute risk, Dr. Retnakaran said, but it is showing that there is a heightened risk such that women and their clinicians need to be aware of and potentially the need for greater preventative care in the future.
“It is allowing you to identify future lifetime risk of cardiovascular disease,” he said.
Study rationale and design
GHTD is “a forerunner of hypertension,” and gestational diabetes is “a precursor of diabetes” – each associated with a high risk of developing CVD in the years after pregnancy, the investigators said. While studies have looked at their individual contributions to future CVD risk, not many had looked to see what risks having both may confer in the postpregnancy years.
For the analysis, data on 886,295 women with GHTD (43,861), gestational diabetes (54,061), both (4,975), or neither (783,398) were obtained from several Canadian administrative health databases.
The mean age was around 30 years across the groups, with those with both conditions or gestational diabetes alone more likely to be older than those with GTHD alone or neither condition (32 vs. 29 years, respectively, P < .001).
After a total follow-up period of 12 years, 1,999 CVD events were recorded, most of them (1,162) 5 years after the pregnancy.
Pregnancy is a stress test for the heart
“We know that what we call adverse pregnancy outcomes – things like gestational hypertension, and gestational diabetes, and preeclampsia – are on the rise globally,” Natalie A. Bello, MD, director of hypertension research at the Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, commented in an interview.
Dr. Natalie Bello
“People who are younger and of childbearing age who are going into pregnancy now are less healthy than they perhaps were in the past,” Dr. Bello suggested, with more hypertension, more obesity, and people being less physically active. “We think that’s translating into some of the pregnancy complications.”
That’s concerning for a number of reasons, said Dr. Bello, who is also the cochair of the American College of Cardiology’s Cardio-Obstetrics Workgroup, and the biggest one perhaps is the stress that these may conditions may be placing on the heart.
“We know that when individuals have an adverse pregnancy outcome like gestational hypertension, or gestational diabetes, their risk for heart disease is increased in the future compared to someone who has an uncomplicated pregnancy,” she said. “So, we sort of say pregnancy is like a stress test for your heart.”
Dr. Bello added that “these situations, these adverse pregnancy outcomes are an indicator for us as physicians, but also they should be for patients as well, to sort of make sure they’re talking to their doctor about their risk factors and modifying them whenever possible.”
The population studied came from quite a racially, ethnically, and economically diverse area of Canada, Dr. Bello pointed out, although because of the nature of an administrative database there wasn’t information on individual level risk factors.
“We don’t know things like smoking, or if individuals were obese when they were pregnant. So, there are some limitations that should be noted,” she said.
Also, the results don’t mean that isolated gestational diabetes “isn’t something we need to be concerned about,” Dr. Bello observed, adding that the study may have been underpowered to look at this association. “It may just be that it will take a longer time for individuals who have gestational diabetes who don’t make lifestyle changes to develop diabetes, and then develop heart disease.”
The main message is that the women who have a co-occurrence of gestational hypertension and gestational diabetes are at particularly high risk of cardiovascular disease in the future,” said Dr. Retnakaran.
“The way to look at it from a patient standpoint is that we are all on different tracks in terms of our cardiometabolic destiny,” and that these data give “some understanding of what kind of tracks they are on for future risk,” Dr. Retnakaran said.
“A history of either gestational hypertension, and/or gestational diabetes should be really a warning sign for physicians and for patients that they have a higher risk of heart disease,” said Dr. Bello.
She added that this is a signal “that we need to do things to modify their risk, because we know that about 80% of heart disease is modifiable and preventable with proper risk factor management.”
The study was funded by the Ontario Ministry of Health and Long-Term Care. Dr. Retnakaran has received grants and personal fees from Novo Nordisk and Merck, grants from Boehringer Ingelheim, and personal fees from Eli Lily Takeda, and Sanofi. Dr. Bello had no conflicts of interest to disclose.