Prepregnancy Cardiovascular Risk Factors Play Role in Risk of Adverse Maternal, Fetal Outcomes

Analysis of more than 18 million pregnancies sheds light on the impact various prepregnancy cardiovascular risk factors, including BMI, smoking status, and diabetes, can have on risk of adverse maternal and fetal outcomes.

A woman’s cardiovascular risk profile could help predict risk of adverse pregnancy outcomes for mother and offspring, according to a new study from Northwestern University Feinberg School of Medicine.

A cross-sectional analysis of maternal and fetal data from the National Center for Health Statistics, results of the study demonstrate the presence or absence of 4 specific cardiovascular risk factors, including BMI and diabetes status, before pregnancy could help predict risk of adverse outcomes, including maternal ICU admission, preterm birth, low birthweight, and fetal death.

"Individual cardiovascular risk factors, such as obesity and hypertension, present before pregnancy have been associated with poor outcomes for both mother and baby," said study lead investigator Sadiya Khan, MD, Assistant Professor of Cardiology and Epidemiology at Northwestern University Feinberg School of Medicine, in a press release from the European Society of Cardiology. "Our study now shows a dose-dependent relationship between the number of risk factors and several complications. These data underscore that improving overall heart health before pregnancy needs to be a priority."

To learn more about how presence of cardiovascular risk factors might influence maternal and fetal outcomes, Khan and a team of colleagues from the Feinberg School of Medicine, including AHA President Donald Lloyd-Jones, MD, designed the current study to identify the total burden of prepregnancy cardiovascular risk factors among pregnant women. Investigators designed their study as cross-sectional analysis of data from the National Center for Health Statistics. Using the database and a time frame of interest defined as 2014-2018, investigators performed a search of patient data related to births to women aged 15-44 years during this time frame.

Cardiovascular risk factors of interest for the investigators’ analysis included BMI, smoking status, presence of hypertension, and presence of diabetes. Patients were categorized according to the number of risk factors present prior to becoming pregnant, with scores ranging from 0-4.

In total, 18,646,512 pregnancies were identified for inclusion. The study cohort had a mean maternal age of 28.6 (SD, 5.8) years, 53.6% were non-Hispanic white, and more than 60% had at least 1 prepregnancy cardiovascular risk factor. Overall, 52.5% reported having 1 risk factor while 7.3%, 0.3% and 0.02% reported having 2, 3, and 4 risk factors, respectively. Compared to their counterparts with no risk factors, women with at least 1 risk factor had lower educational attainment (79.5-85.3% vs 88.7% graduated high school), less receipt of prenatal care (97.8-98.5% vs 98.7%), higher prevalence of multiparty, and a higher prevalence of prior spontaneous or induced pregnancy loss.

In analyses adjusted for maternal age at delivery, race/ethnicity, education, receipt of prenatal care, parity, and birth plurality, investigators found grades associations between increasing number of prepregnancy risk factors and increased risk of adverse outcomes. Compared to those with no risk factors, risk of maternal ICU admission was increased 1.12-, 1.86-, 4.24-, and 5.79-fold increase in risk among those with 1, 2, 3, and 4 risk factors, respectively.

Investigators noted women with all 4 risk factors had a 5.8-fold greater risk of maternal ICU admission, 3.9-fold greater risk for preterm birth, 2.8-fold greater risk of low birthweight, and 8.7-fold greater risk of fetal death compared to those with no risk factors. Investigators also pointed out individual components of the risk factor score were directly associated with adverse outcomes, with heterogeneity in effect sizes; however, this effect was not seen with BMI, which was inversely associated with low birth weight.

“Levels of prepregnancy obesity and high blood pressure are rising and there are some indications that women are acquiring cardiovascular risk factors at earlier ages than before,” added Khan. “In addition, pregnancies are occurring later in life, giving risk factors more time to accumulate. Taken together, this has created a perfect storm of more risk factors, earlier onset, and later pregnancies.”

This study, “Association of pre-pregnancy cardiovascular risk factor burden with adverse maternal and offspring outcomes,” was published in the European Journal of Preventive Cardiology.