March 10, 2021
Being obese and pregnant raises the risk for cardiac complications in women with preexisting heart disease, new research suggests, highlighting the need for earlier interventions in this high-risk population.
The analysis of 790 pregnancies revealed that 23% of women with obesity, defined as body mass index greater than 30 kg/m2, had a cardiac event during pregnancy vs 14% of women with normal body weight (P = .006).
The difference was driven largely by an increase in heart failure (8% vs 3%; P = .02), although arrhythmias also trended higher in obese women (14% vs 10%; P = .19).
Nearly half of the women with obesity and a cardiac event presented in the postpartum period (47%).
In multivariate analysis, both obesity and Canadian Cardiac Disease in Pregnancy Study (CARPREG) II risk score were independent predictors of cardiac events (odds ratios for both, 1.7), the investigators, led by Birgit Pfaller, MD, University of Toronto, Canada, reported this week in the Journal of the American College of Cardiology.
Although obesity has been linked to worse pregnancy outcomes and higher cardiovascular risk after delivery in the general population, the authors note this is the first study to examine its effect on outcomes in women with heart disease.
"We wanted to look at this high-risk group of women that had preexisting heart disease, but in addition had obesity, to try and find out if there was a kind of double hit for these women — and that, in the end, is what we found. It's not just simply having heart disease, not simply having obesity, but the combination that's problematic," senior author and cardiologist Candice Silversides, MD, University of Toronto, told theheart.org | Medscape Cardiology.
The findings are concerning given the rising prevalence of obesity worldwide. National data from 2018 show that slightly more than half of women who gave birth in the United States were significantly overweight or obese before becoming pregnant.
Similarly, in the present analysis of 600 women in the CARPREG study who gave birth from 2004 to 2014, nearly 1 in 5 pregnancies (19%) occurred in women with obesity and 25% were in overweight women.
Obese women were significantly more likely than those without obesity to have coronary artery disease (6% vs 2%), cardiomyopathies (19% vs. 8%) and left ventricular dysfunction (19% vs 12%) and to be hypertensive or have a hypertensive disorder of pregnancy (13% vs 3%).
Preeclampsia developed in 32 women during the index pregnancy and 69% of these women were obese or overweight. Cardiac event rates were similar in women with or without preeclampsia but trended higher in women with preeclampsia with vs without obesity (36% vs 14%; P = .20).
The ill effects of obesity were also reflected in fetal and neonatal events. Overall, 43% of women with obesity and 33% of normal-weight women had at least one fetal event (P = .02), with higher rates of preterm birth (19% vs 10%; P = .005) and respiratory distress syndrome (8% vs 3%; P = .02) in women with obesity. Congenital cardiac malformations were present in 6% of women in both groups.
Taken together, the composite of cardiac events, preeclampsia, or fetal events was significantly more common in women with obesity than in normal-weight women (56% vs 41%; P = .002).
"We've spent the last number of years trying to research and understand what the drivers of these adverse outcomes are in this high-risk pregnant cohort, but on a bigger picture the real issue is how do we start intervening in a meaningful way," Silversides said.
Like many in the burgeoning field of cardio-obstetrics, the team proposes a multidisciplinary approach that stresses preconception counseling, educating pregnant women with heart disease and obesity about their risks, ensuring that dietary advice, weight gain recommendations, and comorbidities are addressed as part of routine care, and providing postpartum surveillance.
Preconception screening "has been the recommendation for a long, long time; it's just that it doesn't always happen in reality," she said. "Many pregnancies aren't planned and not all women are filtered into preconception counseling. So sometimes you'll do it at the first antenatal visit and try to ensure women are educated but optimally you want to do it well in advance of pregnancy."
Part of that preconception counseling "should also include giving them appropriate advice for contraception, if what they want to do is avoid pregnancy," added Silversides.
Garima Sharma, MD, Ciccarone Center for the Prevention of Cardiovascular Disease, Johns Hopkins University School of Medicine, Baltimore, Maryland, and colleagues write in an accompanying editorial that the adverse events observed in this high-risk cohort have "important implications for cardio-obstetricians and should be incorporated in routine pre-pregnancy and antenatal counseling, monitoring, and risk stratification for women with existing cardiovascular disease."
They point to a paucity of data incorporating maternal prepregnancy obesity and gestational weight gain in risk prediction and call for larger population-based studies on the additive impact of obesity severity on predicting adverse cardiac events in women with existing cardiovascular disease.
Randomized trials are also urgently needed to evaluate the effect of nutritional and behavioral interventions in pregnancy on short- and long-term outcomes in mother and child.
"As the obesity epidemic continues to grow and public health interventions promoting lifestyle changes for obesity management remain a major challenge, maternal obesity may prove to be the 'Achilles' heel' of sustainable national efforts to reduce maternal mortality and improve health equity. This is a call to action," Sharma and colleagues conclude.
The investigators note that the study was conducted at a single-center and used self-reported pregnancy weight collected at the first antenatal visit, which may have underestimated obesity rates. Other limitations are that weight changes over the course of pregnancy were not studied and there was a limited number of women with a body mass index of 40 kg/m2 or higher.
The study was supported by a grant from the Allan E. Tiffin Trust, Toronto General and Western Hospital Foundation, and by a donation from Mrs. Josephine Rogers, Toronto General Hospital. Silversides is supported by the Miles Nadal Chair in Pregnancy and Heart Disease. The editorialists Sharma, Roger Blumenthal, MD, and Athena Poppas, MD, have disclosed no relevant financial relationships.