On your first pregnancy and looking for a reason to work out? Here's one: Women pregnant with their first child who exercise regularly trim their risk of having a too-heavy baby, new research from Norway shows. That's true regardless of how much exercise the women got - or didn't get - before becoming pregnant.
Women who deliver excessively large babies, defined as newborns weighing in at more than 4 000 grams or 8 pounds, 13 ounces no matter what their length, are at risk of a number of complications, such as heavy bleeding after delivery, note study co-author Dr Katrine Mari Owe of the Norwegian School of Sport Sciences and her colleagues. These babies may also themselves be at greater risk of obesity later on.
More and more of these extra-large babies are being born, they add, while women are exercising less and less.
Given the bad effects associated with heavy babies, even though the study only showed a difference among women who are pregnant for the first time, health care workers "should promote regular exercise during pregnancy for the purpose of prevention," the authors conclude.
How the study was done
Owe and her colleagues analysed data from the Norwegian Mother and Child Cohort Study and the Medical Birth Registry of Norway on 36 869 single pregnancies.
More than one in ten of the babies were too heavy, meaning their weights topped the 90th percentile, the researchers found, and more than half of these big infants were born to mothers who had already had children.
Among women pregnant with a first child, the researchers found, those who reported exercising at least three times a week during their 17th week of pregnancy were about a quarter less likely to have an excessively heavy baby.
Women who exercised at least three times weekly at 30 weeks' pregnancy were 22% less likely to have a too-big baby.
Of note: The amount of exercise women did before pregnancy had nothing to do with their likelihood of having an overly large newborn.
No ‘gold standard’ in exercise in pregnancy
Exercise could help prevent foetuses from growing too large by helping maintain the body's ability to keep blood sugar levels under control, the researchers note.
High blood sugar and diabetes that develops temporarily during pregnancy are risk factors for having a very large baby.
To date, Owe and her team note, there have been no gold standard trials to investigate the effects of regular exercise in pregnancy on the risk of having an excessively heavy infant.
"There seems to be an urgent need" for them, they conclude. – (Reuters Health, September 2009)
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