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Physical exercise during pregnancy and fetal growth measures: a study within the Danish National Birth Cohort
Mette Juhl1, Jørn Olsen, Per Kragh Andersen
1National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark. metjuhl@gmail.com
Insights
Physical exercise during pregnancy is linked to slightly smaller babies, but poses no significant risk to fetal growth. Moderate exercise may decrease the risk of both small and large for gestational age infants.
Area of Science:
- Obstetrics and Gynecology
- Maternal-Fetal Medicine
- Exercise Physiology
Background:
- Physical activity during pregnancy is encouraged for maternal health.
- Limited data exists on the specific impact of maternal exercise on fetal growth parameters.
Purpose of the Study:
- To investigate the association between regular physical exercise during pregnancy and various fetal growth metrics.
- To determine if maternal exercise influences birth weight, length, body composition, and gestational age-adjusted size.
Main Methods:
- Analysis of data from 79,692 singleton births in the Danish National Birth Cohort (1996-2002).
- Calculation of mean differences in fetal growth measures (birthweight, length, ponderal index, circumferences, placental weight).
- Assessment of risks for small-for-gestational-age (SGA) and large-for-gestational-age (LGA) infants using hazard ratios.
Main Results:
- Exercising mothers had infants with slightly lower birth weights and lengths compared to non-exercisers, with minimal statistical significance.
- A modest reduction in the risk of delivering SGA infants (HR 0.87) and LGA infants (HR 0.93) was observed in exercising women.
- No substantial adverse effects on other fetal growth measures were detected.
Conclusions:
- Maternal physical exercise during pregnancy does not lead to significant adverse effects on fetal growth.
- Exercise is associated with a modest decrease in the risk of both SGA and LGA infants.
- Findings support current recommendations for pregnant women to remain physically active.
Objective:
The objective of the study was to examine the association between physical exercise during pregnancy and fetal growth measures.
Study Design:
Data on 79,692 liveborn singletons from the Danish National Birth Cohort were collected between 1996 and 2002. Mean differences in birthweight, length, ponderal index, head and abdominal circumference, and placental weight and hazard ratios of small- and large-for-gestational-age babies were calculated.
Results:
Our data indicated smaller babies in exercising women compared with nonexercisers, but the differences were small, and only a few were statistically significant. Exercising women had a slightly decreased risk of having a child small for gestational age (hazard ratio, 0.87; 95% confidence interval, 0.83-0.92) and large for gestational age (hazard ratio, 0.93; 95% confidence interval, 0.89-0.98).
Conclusion:
The findings do not indicate sizable effects on fetal growth measures related to exercise apart from a modest decreased risk of small- and large-for-gestational-age infants. These findings do not speak against advising pregnant women to be physically active during pregnancy.
