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
