Breast isn't just best for baby: mothers who don't breastfeed their babies may
increase their risk of heart attacks and strokes decades later, new research
suggests.
The evidence comes from the massive Women's Health Initiative trial and involved
nearly 140,000 women.
Researchers found that women who breastfed were less likely when they were older
to have developed high blood pressure, diabetes, high cholesterol and
cardiovascular disease — the leading cause of death in Canadian women.
"The longer a woman breastfed her baby, the better it was for both of them,"
says lead author Dr. Eleanor Bimla Schwarz, of the University of Pittsburgh.
"We know that women who don't breastfeed their babies are at a higher risk of
getting breast cancer and ovarian cancer," Schwarz says. Recent studies show
women who don't breastfeed also have higher risks of diabetes and high blood
pressure.
"Ours is the first study that shows that there really is a strong effect in
terms of preventing heart attacks and stroke for women who nursed for more than
six months," says Schwarz, an assistant professor of medicine, epidemiology and
obstetrics, gynecology and reproductive sciences.
The study appears in the latest issue of Obstetrics and Gynecology.
Health Canada recommends breast milk should be the only food or drink for the
first six months of life, and that breastfeeding continue, along with the
gradual introduction of solid food, for two years or more. But a national survey
released last month found only 14 per cent of new moms in Canada were
exclusively feeding their newborns breast milk by age six months.
Breastfeeding helps protect babies against infections and disease, benefits that
are thought to last a lifetime.
"We now know that it's important for mothers' health as well," Schwarz says.
Her team analyzed data from 139,681 post-menopausal women, average age 63,
enrolled in the Women's Health Initiative study, known best for its research on
hormone replacement therapy. Researchers looked at the women's lifetime history
of breastfeeding, meaning how many months in total they had breastfed their
babies.
Women who had breastfed for one to six months had less diabetes, less high blood
pressure and less high cholesterol, all known risk factors for heart disease.
Those who breastfed for seven months or more were significantly less likely to
have actually developed cardiovascular disease compared to women who had never
breastfed. Women who breastfed for a lifetime total of at least 12 months were
10 per cent less likely to have had a heart attack or stroke or developed heart
disease when they were older.
The finding held after researchers took age, income, body mass index, diet,
physical activity, family history of heart disease and other factors into
account.
For Schwarz, the study was personal. "As a new mom who went back to work, I
found pumping a bit challenging," Schwarz says. "Everybody kept telling me it
was good for my baby. I wondered what effect it had on my own health."
Fat stores accumulate during pregnancy, and other studies have shown that, in
populations where breastfeeding is rare, pregnancy might increase the risk of
heart disease.
One theory is that breastfeeding lowers that risk by mobilizing fat stores.
"Breastfeeding has an important role in the way women's bodies recover from
pregnancy,"Schwarz says. "I think what we're seeing is that when this process is
interrupted by women feeding their babies things other than human milk, women
are more likely to have a number of health problems."
When milk isn't expressed, she said, women don't unload all the body fat stored
up during pregnancy.
Prolactin and oxytocin, hormones involved in producing milk and releasing it
from the body, may also have effects on a woman's heart.
The study doesn't prove cause and effect, just an association, and there may be
other issues at play, cautions Dr. Beth Abramson, a Toronto cardiologist and
spokeswoman for the Heart and Stroke Foundation. For example, women who choose
or are able to breastfeed may have less stressful lives.
"They may be in a different economic bracket because they may not at that time
have had to go back to work. You sometimes can't correct for everything.
"If a woman is considering breastfeeding, this may be another potential
benefit," Abramson says, "but if a woman has, for various reasons, chosen not
to, or can't breastfeed, not all hope is lost. There are a lot of healthy
behaviours we can engage in to reduce our risk of heart disease and stroke,"
such as not smoking or quitting, keeping physically active and managing weight.
Source : Canwest News Service
