Pregnant after 40? Study suggests higher lifetime risk of heart attack, stroke

Pregnant belly
Numerous factors play a role in preterm birth. Risks include pregnancy before age 17 or after 40, having twins or more, and the mother's own health, such as being underweight or overweight, having diabetes or high blood pressure, and whether she smokes. CLAUDIO SANTANA/AFP/GettyImages

New research is warning that women who become pregnant at age 40 or older are at a greater risk of stroke and heart attack later in life.

While older moms are already at risk of complications during their pregnancy, U.S. doctors say they also need to pay attention to their cardiovascular health in subsequent years. They say their findings are especially relevant as more women delay motherhood.

“We already knew that older women were more likely than younger women to experience health problems during their pregnancy. Now we know that the consequences of that later pregnancy stretch years into the future,” Dr. Adnan Qureshi, lead researcher and a University of Minnesota professor, said in a statement.

“Women with a late pregnancy need to be aware of their increased risk and take steps to improve their cardiovascular health. And their doctors need to remain vigilant years later in monitoring these women’s risk factors,” Qureshi said.

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READ MORE: Here’s how women’s heart attack symptoms differ from men’s

For his research, presented Wednesday night at the American Stroke Association’s conference, Qureshi looked at data from more than 72,000 women who were between 50 and 80 years old. About 3,300 women were pregnant later on in life from that group – the scientists looked at their rates of stroke, heart attack and death from heart disease over the next 12 years compared to women who were pregnant at a younger age.

Turns out, women who were pregnant at age 40 and above had an elevated risk of heart issues compared to their peers who were younger moms.

Risk of ischemic stroke – stroke caused by a clot – went from 2.4 per cent in young moms to 3.8 per cent.

Risk of hemorrhagic stroke – stroke caused by a brain bleed – was raised from 0.5 per cent to one per cent.

And risk of heart attack increased from 2.5 per cent to three per cent. Death from all forms of heart disease went from 2.3 per cent in average moms to 3.9 per cent in older moms.

READ MORE: Male heart attack patients receive faster care than women, Canadian study suggests

When the doctors checked for well-known risk factors for heart disease – high blood pressure, diabetes, high cholesterol – they learned that it was these factors that explained why older moms were at an increased risk.

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The findings are preliminary, though. The age of women at their last pregnancy hasn’t been considered a risk factor for stroke and heart attack before.

Dr. Jacob Udell, a cardiologist at Women’s College Hospital in Toronto and spokesperson for the Heart and Stroke Foundation, said the medical community is trying to piece together why older moms are at a higher risk of heart disease.

“We’re doing a fantastic job reducing death from heart attack and stroke but…we’re having a hard time figuring out why 40 to 60 year olds are having this stubbornly low rate of decline in risk of dying from heart disease,” he said.

READ MORE: Developing diabetes in pregnancy on the rise, Canadian study warns

He suggests there are theories circulating – perhaps it’s the Western lifestyle. Younger women were taking up smoking for a time, and weight has been creeping up as global health officials grapple with an obesity epidemic.

But another theory that’s taken hold is the notion that fertility therapy may be playing a role.

“Something about women that’s different from men is the differences in hormones, especially before menopause. We start to see risk track more similarly after menopause, but there’s also an introduction in fertility therapy for women to have more pregnancies in their 40s. This opens a slew of questions,” Udell said.

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Right now, Heart and Stroke doctors are comparing the heart health outcomes of women who underwent fertility treatments and had success with pregnancy, women who didn’t find success and women who didn’t use fertility therapy at all.

Some women also encounter pre-eclampsia – high blood pressure during pregnancy – and gestational diabetes. They’re both risk factors for heart disease.

READ MORE: Do babies inherit junk food addictions from their moms?

Udell said researchers are also trying to learn if younger moms can recover from these diagnoses better than their older counterparts.

For now, he’s telling Canadians moms not to worry.

“Don’t be alarmed. The risk is low, but there may be a particular set of women who need a good check-up by their family doctors to identify risk factors for heart disease,” he said.

Read more about the research here.