Study Highlights BMI, Adverse Pregnancy Outcomes as Markers for CVD Risk

Experiencing obesity prior to conception and during the early stages of pregnancy was shown to be a strong indicator of increased susceptibility to future cardiovascular issues, according to a study published in Circulation Research.¹

Specifically, obesity was significantly associated with adverse pregnancy outcomes (APOs) such as elevated blood pressure, preeclampsia, and gestational diabetes. While obesity is generally understood as a risk factor for both cardiovascular disease (CVD) and pregnancy-related blood pressure complications, it was previously unclear which of these factors—obesity or pregnancy complications—had a more significant impact on an individual's long-term CVD risk following pregnancy.

The current study assessed the links between body mass index (BMI), APOs, and postpartum CVD risk factors.

“Looking for ways to support and optimize a person’s cardiovascular health is still of the utmost importance if someone has had an adverse pregnancy outcome,” said Sadiya S. Khan, MD, lead author of the study, preventive cardiologist, and associate professor of medicine at Northwestern University Feinberg School of Medicine, in a press release.² “However, if we really want to make a difference in improving cardiovascular health and preventing these pregnancy outcomes, we have to shift to the pre-pregnancy and early pregnancy space.”

Pregnant woman consulting with doctor | Image Credit: pressmaster – stock.adobe.com

The study included 4216 adults recruited from the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-To-Be (nuMoM2b) Heart Health Study, who were initially enrolled during their first trimester of pregnancy—defined as 6 weeks to 13 weeks and 6 days gestation—across 8 different locations in the United States. These participants had a follow-up visit approximately 3.7 years after giving birth, and the mean (SD) maternal age was 27 (6) years. APOs were assessed centrally and encompassed conditions like hypertensive disorders during pregnancy, preterm birth, giving birth to babies smaller than expected for their gestational age, and gestational diabetes.

In the early stages of pregnancy, 25% of enrolled individuals were classified as overweight with a BMI between 25 and 30 kg/m², and 22% were classified as obese with a BMI of at least 30 kg/m². During pregnancy, 15% of participants experienced hypertensive disorders, 8% had preterm births, 11% gave birth to babies smaller than expected for their gestational age, and 4% developed gestational diabetes.

Compared with individuals with a “normal” BMI—defined as less than 25 kg/m2—during early pregnancy, even after adjusting for baseline CVD risk factor levels, those with obesity had a significantly higher risk of developing:

• postpartum hypertension (adjusted OR [aOR], 1.14; 95% CI, 1.10-1.18)
• hyperlipidemia (aOR, 1.11; 95% CI, 1.08-1.14)
• diabetes (aOR, 1.03; 95% CI, 1.01-1.04)

Meanwhile, APOs were also linked to a higher risk of postpartum hypertension (aOR, 1.97; 95% CI, 1.61-2.40) and hyperlipidemia (aOR, 1.31; 95% CI, 1.03-1.67).

Hypertensive disorders during pregnancy accounted for a small portion of the link between obesity and the development of postpartum hypertension—13% with a range of 11% to 15%—but did not mediate the connections with postpartum hyperlipidemia or diabetes. There was no significant mediation by preterm birth or giving birth to smaller-than-expected babies for gestational age.

“This contributes to the growing evidence base that APOs largely represent a marker of preexisting CVD risk that is unmasked during pregnancy and suggests growing emphasis on early pregnancy or prepregnancy interventions before an APO occurs,” the study authors said.

References

1. Khan SS, Petito LC, Huang X, et al. Body mass index, adverse pregnancy outcomes, and cardiovascular disease risk. Circ Res. 2023;133(9):725-735. doi:10.1161/CIRCRESAHA.123.322762
2. Pregnancy complications increase and unmask short- and long-term cardiovascular risk for people with obesity. News release. National Institutes of Health. October 10, 2023. Accessed October 20, 2023. https://www.nih.gov/news-events/news-releases/pregnancy-complications-increase-unmask-short-long-term-cardiovascular-risk-people-obesity