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Health and wellness

Breastfeeding for six months cuts diabetes risk in women by nearly half, study finds

Also in the news: women who start menstruation or enter menopause at a younger age more at risk from stroke or heart disease, and night shift work increases cancer risk among some women, studies suggest

PUBLISHED : Thursday, 18 January, 2018, 6:17pm
UPDATED : Thursday, 18 January, 2018, 6:17pm

Women who breastfeed their babies for six months or more may be able to cut their risk of developing diabetes in the future by nearly half, according to a study released on Tuesday.

The findings from a three-decade US study of more than 1,200 women were published in The Journal of the American Medical Association.

“We found a very strong association between breastfeeding duration and lower risk of developing diabetes, even after accounting for all possible confounding risk factors,” says lead author Erica Gunderson, senior research scientist with Kaiser Permanente.

Women who breastfed for six months or more had a 47 per cent reduction in their risk of developing type 2 diabetes, compared to those who did not breastfeed at all.

Women who breastfed for six months or less saw a 25 per cent reduction in diabetes risk.

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Researchers suggest that breastfeeding may unleash protective effects through hormones that act in the pancreas, controlling insulin levels and blood sugar.

“The incidence of diabetes decreased in a graded manner as breastfeeding duration increased, regardless of race, gestational diabetes, lifestyle behaviours, body size, and other metabolic risk factors measured before pregnancy, implying the possibility that the underlying mechanism may be biological,” says Gunderson.

Previous research has shown that breastfeeding has other long-term benefits for mothers, including a lower risk of breast and ovarian cancer.

Early menstruation and menopause linked to higher risk of heart disease, stroke

Women who started menstruating at the age of 11 or younger, or entered menopause before 47, face a higher risk of heart disease and stroke, according to a study published on Tuesday.

Miscarriage, stillbirth, undergoing a hysterectomy, and bearing children at a young age were also associated with elevated odds of cardiovascular problems later in life, researchers found.

The additional risk varied from only a few percentage points to more than 40 per cent, they reported in the journal Heart.

The findings are not the first to uncover a link between reproductive factors and cardiovascular diseases, and the data do not show a causal relationship, the authors caution.

The findings do strengthen the association, and suggest that women with premature reproductive cycles or a history of adverse events should be frequently screened for heart trouble and conditions leading to blood clots.

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The scientists drew data from a long-term health survey in Britain that monitored and tested more than 250,000 women from 2006 to 2016. The women’s average age was 56 when monitoring began.

More than 80 per cent had been pregnant, and nearly half had two children. On average, they started having their periods at 13, and had their first child at 26.

In 2016, two-thirds of the women had gone through menopause, at an average age of 50.

The study showed that women who began menstruating before the age of 12 faced a 10 per cent greater risk of cardiovascular disease compared to those who were 13 or older.

For those who went through menopause before the age of 47, the risk for cardiovascular disease rose by 33 per cent, and for stroke by 42 per cent.

Miscarriages were likewise linked with a greater danger of heart disease, with each stillbirth increasing the risk by six per cent.

A hysterectomy was associated with a 20 per cent higher chance of developing heart disease, the team found.

Women working night shifts in Europe and North America at higher risk of cancer

Women who regularly work night shifts in Europe and North America may face a 19 per cent higher risk of cancer than those who work during the day, a recent study shows.

These heightened risks were not apparent among female night-shift workers in Australia and Asia, according to the meta analysis in the journal Cancer Epidemiology, Biomarkers and Prevention.

“Our study indicates that night shift work serves as a risk factor for common cancers in women,” says study author Xuelei Ma, an oncologist at the West China Medical Centre of Sichuan University in Chengdu, China.

“We were surprised to see the association between night shift work and breast cancer risk only among women in North America and Europe,” he says.

“It is possible that women in these locations have higher sex hormone levels, which have been positively associated with hormone-related cancers such as breast cancer.”

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The review incorporated 61 previously published studies on the topic, spanning 3.9 million participants from North America, Europe, Australia, and Asia and more than 110,000 cases of cancer.

One drawback to the study was that the different definitions of long-term night shift work – with some of the papers describing it as “working during the night” and others saying “working at least three nights per month”.

While overall long-term night shift work increased the risk of cancer by 19 per cent, the risk of certain cancers was even higher.

Female night shift workers saw a 41 per cent increased risk of skin cancer and a 32 per cent higher risk of breast cancer.

The results of this research suggest the need for health protection programmes for long-term female night-shift workers
Xuelei Ma, study author

The risk of gastrointestinal cancer was 18 per cent higher than in women who did not perform long-term night shift work.

When it came specifically to breast cancer, the risk rose by 3.3 per cent for every five years of night shift work.

Previous research has shown that night work can disrupt the body’s circadian rhythms, causing hormonal and metabolic changes that may boost the risk of cancer, diabetes, obesity and depression.

“The results of this research suggest the need for health protection programmes for long-term female night-shift workers,” said Ma.

“Long-term night shift workers should have regular physical examinations and cancer screenings.”