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Exercise for moms-to-be may help them avoid having bigger babies

September 22, 2009 | 10:39 am

Babies are being born bigger, which isn't necessarily a good thing -- a high birth weight is associated with numerous complications for both mother and child, plus obesity.

But regular exercise during pregnancy may decrease the chance of giving birth to babies with excessive birth weight, according to a new study.


Researchers in Norway examined data from 36,869 single pregnancies documented in the Norwegian Mother and Child Cohort Study, in which women were asked about their exercise habits. Among those pregnancies, 4,033 babies were born with excessive weight, defined by being in the 90th percentile for weight. More of those heavyweight newborns were born to women who had previously given birth (2,263) than first-time moms (1,770).

More differences were found: Women who had given birth before didn't exercise and tended to be more overweight compared with women who hadn't had a baby.

First-time mothers who exercised at least three times a week during their pregnancy, however, were less likely to give birth to a baby with excessive birth weight, even when the researchers controlled for high blood pressure, diabetes and preeclampsia. Although the results referred to exercise during pregnancy, the researchers point out that women who exercise regularly before becoming pregnant are likely to continue working out throughout their pregnancy.

Although the relationship between exercise and excessive birth weight wasn't as clear cut for women who had previously given birth, researchers believe exercise may provide an overall protective effect on excessive birth weight.

The study appears in the October issue of the journal Obstetrics & Gynecology.

-- Jeannine Stein

Photo credit: Ricardo DeAratanha / Los Angeles Times

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Comments (7)

I don't know about this study. I exercised 1 hr 5 times a week while pregnant with my two kids, up and until the very last day of pregnancy. I had two huge boy babies (8 14 and 9 8) naturally and never has my doctor stated the babies were "overweight". They and I are healthy, athletic, muscular and I'll take that any day over sluggish and skinny. They were always at 95 to over 100 percentile, but never fat. So, they will grow to be 6'6" and 6'3" from what the doctors say and I'm glad they will be "manly men". It's about the quality of food kids and adults take in and the amount of every day exercise.

I also don't agree with this study. I had a big baby for my first 9lbs 15oz., and I exercised regularly my whole pregnancy by swimming and walking.

It depends on alot of factors before during and after pregancy.Diabeties plays a significant factor of delivering large birth weight newborns no matter how much exercise to you do.Gaining too much weight,poor prenatal care adds to large birth weight newborns.

I also exercised at least 4-5 times a week with good diet till the end and had a "big" baby at 8.5 pounds naturally. I only gained 33 pounds during the whole pregnancy. She's consistently over 95% but proportionate all around even now at 10 months and the doctor has never once said she's overweight! She's quite happy at her progress and my daughter's quite active!

There are always exceptions. The study is making general conclusions.

Birthweight of 90th percentile is about 8lbs 12 oz for a girl and 9 lbs 4 oz for a boy.

So, most of you who have commented have had "normal" sized babies, not "huge". Since you exercise regularly and have a "normal" baby, your personal experience actually supports the results of the study.

Obviously the study is not generalizing to all women. However, there is a TENDENCY for overweight non-exercisers to have larger babies. OF COURSE there are exceptions in both directions. Just because you are an exception does not mean that the study, which states a TREND, is not accurate.

p.s. There's no such thing as "over 100 percentile". You can be over the 99th percentile, (meaning, "larger than 99% of all babies." The 100th percentile would mean thhat your baby is the largest baby ever born. Above 100th percentile does not exist.

I don't agree with this study. I didn't exercise at all and had a 6 lb. baby. He has always been in the 25th percentile. I haven't even heard of a worry about big babies. I thought there were more health problems to little babies.


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