Death from cardiovascular disease has a new indicator, according to results of a long-term study published in the American Heart Association's journal Circulation. Pregnancy complications appear to be a significant sign of heart disease to come later in life.
According to the American Heart Association (AHA), cardiovascular disease (CVD) is the leading cause of death in the US for both men and women. In 2013, there were 399,503 women who died of CVD.
Data analyzed by researchers at the Public Health Institute's Child Health and Development Studies (CHDS) at Berkeley, CA, shows a high correlation between women who experienced complications during pregnancy and those facing death from heart disease later in life.
During pregnancy, high blood pressure is classified as:
- Pre-existing chronic hypertension - diagnosed when blood pressure is above 140/90 - up to 20 weeks of pregnancy
- Gestational hypertension - diagnosed after 20 weeks - also known as pregnancy-induced hypertension (PIH).
Chronic hypertension and gestational hypertension can lead to preeclampsia - a severe condition that normally occurs after week 20 of pregnancy. Symptoms include high blood pressure and protein in the urine, and it can cause serious complications if not treated quickly.
Previous studies had shown an association linking future CVD with preeclampsia, preterm delivery and small-for-gestational-age delivery.
The current study, led by Barbara A. Cohn, PhD, adds to this that preeclampsia in early pregnancy strongly predicts premature CVD death before age 60.
A study spanning 5 decades
The CHDS enrolled 15,528 pregnant women in the study between 1959 and 1967 and has continued to follow them up. By 2010, a total of 368 of these women, with an average age of 66, had died of CVD. A link was indicated between their cause of death and complications experienced during pregnancy.
Apart from confirming results of previous studies, the current survey also quantified the risk between CVD death later in life and specific combinations of complications.
The following complications increased the risk of death from CVD in women with pre-existing hypertension:
- Delivery of a preterm baby increased CVD death risk 7.1 times
- Preeclampsia increased it 5.6 times
- Small-for-gestational-age delivery increased it 4.8 times
- Preterm delivery increased it five times.
The study also established two new conditions that indicate future heart disease: glycosuria, or high levels of sugar in urine, entailing a 4.2-times greater risk, and hemoglobin decline, where the ability of red blood cells to carry oxygen is reduced. Hemoglobin decline indicated an increased CVD risk of 1.7 times.
Higher risk for African-American women
The researchers were surprised to find that only African-American women (22% of the group) experienced both gestational high blood pressure and CVD. Those who developed it were 1.7 times more likely to die of CVD.
- 6-8% of women develop gestational hypertension
- 5-8% of women develop preeclampsia
- 2-5% of women develop gestational diabetes.
In contrast, white, Asian and Hispanic women in showed no increased risk of CVD due to gestational hypertension.
One limitation of the study is that during pregnancy, women tended to receive full and standard care, which was delivered by one health care provider.
In addition, researchers adjusted for factors such as smoking, body weight, education and occupation. However, after pregnancy, other variables were introduced as women saw different doctors or moved to new areas, which meant that their treatment and lifestyle were no longer uniform.
Despite this limitation, Cohn believes the main goal of defining those women at highest risk for CVD death based on pregnancy complications has been achieved.
Cohn describes pregnancy as a "stress test for the cardiovascular system." She would like doctors to discuss the risk factors with women in an attempt to reduce their risk of heart attack and other cardiovascular diseases.
"One of the wonderful things about cardiovascular medicine is the enormous progress that has been made in preventing death in men and women. These pregnancy complications are early warning signs that tell you to pay attention to risk factors that you can control."
Last month, Medical News Today presented an article investigating a link between antidepressant pills, pregnancy complications and neonatal problems.