The objective of this review was to estimate the influence of structured prenatal exercise on newborn birth weight, macrosomia, and growth restriction. Meta-analysis of included studies showed that prenatal exercise reduced the odds of having a large newborn (birth weight greater than 4,000 g or greater than the 90th percentile for gestational age and sex) by 31% (odds ratio [OR] 0.69, 95% confidence interval [CI] 0.55-0.86; I 25%) without altering the risk of having a small newborn (birth weight less than 2,500 g or less than the 10th percentile for gestational age and sex) (OR 1.02, 95% CI 0.72-1.46; I 0%) or gestational age at delivery (weighted mean difference -0.00 weeks, 95% CI -0.09 to 0.09; I 0%). Newborns of mothers assigned to exercise were lighter than those of nonexercising controls (weighted mean difference -31 g, 95% CI -57 to -4; I 0%). Maternal gestational weight gain (weighted mean difference -1.1 kg, 95% CI -1.5 to -0.6; I 53%) and odds of cesarean delivery (OR 0.80, 95% CI 0.69-0.94; I 0%) were also decreased.
The data examined showed that structured prenatal exercise decreases the risk of having a large newborn without a change in the risk of having a small newborn.