"We already knew that older women were more likely than younger women to experience health problems during their pregnancy," said Adnan I. Qureshi, M.D., lead researcher and director of the Zeenat Qureshi Stroke Institute in St. Cloud, Minnesota. "Now, we know that the consequences of that later pregnancy stretch years into the future."
Qureshi added that this finding was especially important because more women are choosing to have children after they turn forty.
Researchers reviewed data from 72,221 women aged 50 to 79 enrolled in the Women's Health Initiative Study. Of those, 3,306 women reported pregnancies at an advanced age, and researchers compared their rates of stroke, heart attack and cardiovascular death over the next 12 years with women who were pregnant at a younger age.
Researchers found that compared to pregnancy at a younger age, pregnancies at age 40 and older increased the risk of:
- Ischemic stroke (clot caused), the most common type of stroke, from 2.4 percent to 3.8 percent;
- Hemorrhagic stroke (brain bleed), from 0.5 percent to 1 percent;
- Heart attack from 2.5 percent to 3 percent; and
- Death from all forms of cardiovascular disease from 2.3 percent to 3.9 percent.
When researchers checked for well-known risk factors for cardiovascular disease, including high blood pressure, diabetes and high cholesterol, they found these factors explained most of the higher risk the older pregnant women faced. However, these established risk factors did not explain the link between advanced age pregnancy and stroke caused by a brain bleed. Researchers said this link needs further research. Hemorrhagic stroke accounts for about 13 percent of all strokes, according to the American Heart Association's 2016 Statistical Update.
Qureshi also noted that the only cardiovascular risk factor that did not increase with later pregnancies in the study population was smoking. Older pregnant women were less likely to smoke than younger women.
The age of last pregnancy has not been considered a risk factor for stroke, heart attack and other cardiovascular diseases. "However, women with a late pregnancy need to be aware of their increased risk and take steps to improve their cardiovascular health," he said. "And their doctors need to remain vigilant years later in monitoring these women's risk factors through physical examination and, perhaps more tests and earlier interventions to prevent stroke and other cardiovascular events."