Scientists have examined the associations between cardiovascular problems before a pregnancy and complications during labor or pregnancy, and found strong links. Four factors that influence cardiovascular health were considered in the study: unhealthy body weight, diabetes, hypertension, and smoking. The more of these characteristics a woman had, the higher the chance of an adverse outcome in pregnancy, which included low birthweight, preterm birth, maternal intensive care unit (ICU) admission, and fetal death. Over 18 million pregnancies were considered as part of this study, which was reported in the European Society of Cardiology.
"We're not surprised that obesity or hypertension are associated with higher risk of adverse pregnancy outcomes, but what is striking is that we found that with each additional risk factor, the risk of adverse pregnancy outcome gets successively higher," said the corresponding author of the study Dr. Sadiya Khan, an assistant professor of medicine and of preventive medicine at Northwestern University Feinberg School of Medicine. "The sum of all the risk factors is greater than the individual parts."
The study authors suggested that doctors should conduct more comprehensive examinations that take many facets of cardiovascular health into account before a pregnancy occurs, instead of focusing on risk factors like blood pressure or body mass index on their own, noted Khan.
Khan acknowledged that not all pregnancies are planned, but added that women would ideally be evaluated long before they got pregnant, "so there is time to optimize their health," Khan said. "We also need to shift our focus toward prioritizing and promoting women's health as a society so instead of just identifying hypertension, we prevent blood pressure from becoming elevated in the first place."
This study included data from 18,646,512 pregnancies. The mothers in the study were an average of 28.6 years old. Risk factors were assigned based on how many risk factors were present in an individual. No risk factors got a score of zero, and there was one point assigned each for factor. There was one risk factor in 52.5 percent of the women in the study, 7.3 percent had two risk factors, 0.3 percent had three, and 0.02 percent had all four risk factors. Compared to women with no risk factors at all, those with one factor had a 1.12 times greater likelihood of maternal ICU admission; those with two risk factors were 1.86 times more likely; three risk factors made women 4.24 times more likely, and four risk factors conferred a 5.79 times greater chance of ICU admission.
Women are also deferring pregnancy and giving these risk factors more time to build up, and rates of high blood pressure and obesity before pregnancy are rising, added Khan. "Taken together, this has created a perfect storm of more risk factors, earlier onset and later pregnancies," Khan said.