Mothers who followed a supervised exercise program throughout pregnancy gave birth to babies with a lower BMI and reduced odds of being overweight at 12 months, providing new clues about how prenatal lifestyle shapes early growth trajectories.
Study: Exercise during pregnancy and infant BMI during the first year of life: a per-protocol secondary analysis of a randomized clinical trial. Image credit: New Africa/Shutterstock.com
Supervised exercise sessions during pregnancy may improve a child’s BMI trajectory and growth pattern during late infancy, according to a new study published in . Frontiers of global women’s health.
How maternal health shapes infant growth
Pregnancy is a period of dramatic physiological changes that can impact the long-term metabolic health of both mother and child, increasing the risk of developing obesity and other cardiometabolic diseases later in life. Maternal metabolic disorders before and during pregnancy, such as prepregnancy obesity, excessive weight gain during pregnancy, and gestational diabetes, have been linked to the global epidemic of childhood overweight and obesity.
Given the global prevalence of childhood obesity and its psychological and emotional impact, this study aimed to investigate the effects of a supervised exercise program on children’s weight, body mass index (BMI), and early growth trajectory up to 1 year of age.
Randomized trial tracking mother-infant pairs
The study population consisted of 126 mother-infant pairs. Pregnant women were recruited during routine obstetric visits between 8 and 10 weeks of pregnancy. They were randomly assigned to an intervention group and a control group.
Participants in the intervention group performed a supervised exercise program throughout their pregnancy. The program consisted of three weekly 60-minute sessions that included aerobic exercise, muscle strengthening, balance exercises, stretching, and pelvic floor muscle training.
Participants in the control group, on the other hand, received standard obstetric care and educational materials on physical activity, nutrition, sleep hygiene, smoking cessation, and urinary incontinence, but did not participate in supervised exercise sessions.
Infant weight, height, BMI, and feeding type were assessed at 1, 2, 4, 6, and 12 months of age.
Differences in BMI appear in late infancy
The estimated parameters revealed that changes in infant BMI were comparable between groups until 6 months of age. However, at 12 months, infants born to mothers in the intervention group had significantly lower BMI than infants born to mothers in the control group. Similarly, infants born to mothers in the control group were more likely to be classified as overweight at 4 months of age, which persisted until 12 months of age.
Regarding maternal outcomes, the study found that women in the intervention group gained significantly less weight during pregnancy and were more likely to exclusively breastfeed during early infancy compared to women in the control group.
An early divergence in growth trajectory is suggested.
This study highlights the potential importance of supervised exercise during pregnancy, not only in managing maternal weight during pregnancy, but also in shaping infant growth patterns during the first year of life. The observed group differences in mean BMI of infants at 12 months of age further suggest that maternal healthy lifestyle behaviors during pregnancy, particularly physical activity, may be associated with a reduced risk of developing obesity-related growth patterns in children.
During the first year of life, infants undergo rapid and dynamic changes in growth and body composition. Changes in BMI over this period may not accurately predict the risk of developing obesity later in life. For this reason, the researchers advise that these findings should not be interpreted as evidence of sustained effects or long-term obesity prevention.
According to the researchers, these findings should be considered as evidence for an early divergence in growth trajectories that may be influenced by prenatal (prenatal) and early postnatal (postnatal) factors. Future large-scale, long-term studies are needed to understand whether the observed benefits persist, attenuate, or amplify over time.
Of note, this study found higher rates of exclusive breastfeeding among women in the intervention group during the first 6 months after pregnancy. This finding is particularly important because exclusive breastfeeding is known to lead to better growth patterns in infants and a lower risk of childhood overweight and obesity.
Researchers note that breastfeeding may be one potential pathway linking prenatal exercise and infant growth outcomes. but, No formal mediation analysis was performed. In other words, this study cannot determine whether the observed differences in infant BMI can be directly explained by higher breastfeeding rates.
However, several environmental factors such as complementary feeding, diet composition, feeding habits, and broader family lifestyle behaviors may also potentially contribute to early childhood growth trajectories. These factors were not considered in the study analysis and therefore their potential influence on the observed associations cannot be excluded.
The beneficial maternal outcomes of reduced gestational weight gain observed in the intervention group provide further support for infant outcomes, as excessive gestational weight gain is known to increase the risk of childhood obesity.
Overall, these exploratory and hypothesis-generating findings support the clinical relevance of incorporating preventive interventions related to physical activity during pregnancy to improve early childhood growth trajectories.
However, the researchers stress that the results should be interpreted with caution as this was a secondary exploratory analysis, infant BMI results were not the primary endpoint of the original trial, and participant attrition during follow-up was large.
This study primarily enrolled healthy pregnant women without significant obstetric or metabolic complications, which may limit the generalizability of the results to a broader clinical population.
Additionally, infants were only followed for the first year of life. Because infant growth trajectories are dynamic, the long-term clinical significance of the observed modest effects remains uncertain.
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