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Fit Pregnancy, Fit Babies
Reported April 09, 2010
(Ivanhoe Newswire) -- Pregnant women who engage in regular
moderate-intensity aerobic exercise will have babies whose birth weight is
slightly lower without restricting the development of maternal insulin
resistance, which is essential in maintaining nutrient availability to the
fetus.
Increased size at birth is associated with greater risk for the development
of childhood obesity. This study is the first to demonstrate a significant
effect of non-weight bearing exercise, such as stationary cycling, on birth
weight.
"Our findings show that regular aerobic exercise alters the maternal
environment in some way that has an impact on nutrient stimulation of fetal
growth, resulting in a reduction in offspring birth weight," co-author Paul
Hofman, M.D., of the University of Auckland in New Zealand, was quoted as
saying. "Given that large birth size is associated with an increased risk of
obesity, a modest reduction in birth weight may have long-term health
benefits for offspring by lowering this risk in later life."
This study also evaluated changes in insulin sensitivity in response to
aerobic exercise during pregnancy. Maternal insulin resistance has been
correlated with birth size. Exercise has been shown to reduce insulin
resistance, but findings from this study suggest that regular exercise
during pregnancy does not cause the same reduction in insulin resistance
that occurs in exercising non-pregnant individuals.
"The physiological response to pregnancy appears to supersede the chronic
improvements in insulin sensitivity previously described in response to
exercise training in non-pregnant individuals," Dr. Hofman said. "This may
be an important finding for athletes who want to continue regular training
during their pregnancy, as it suggests that training will not have a major
adverse impact on insulin resistance."
In this trial, researchers assigned 84 first-time mothers to either exercise
or control groups. Participants in the exercise group utilized stationary
cycling and were individually prescribed a maximum of five 40-minute
sessions of aerobic exercise per week. The exercise group was instructed to
maintain the exercise program until at least 36 weeks gestation. Insulin
sensitivity was assessed at 19 and 34 to 36 weeks gestation using an
intravenous glucose tolerance test. Birth weight and BMI at birth were
measured within 48 hours of birth.
Exercise training had no effect on maternal body weight or BMI during late
pregnancy. Furthermore, exercise had no effect on insulin resistance from
baseline to late gestation, and did not affect any other parameters of
glucose regulation. Offspring of exercisers were on average lighter than
their control counterparts, although there was no difference in birth
length. Exercise training also resulted in lower BMI for the babies.
SOURCE: Journal of Clinical Endocrinology & Metabolism (JCEM), April 5,
2010 |
