STUDY: Balanced Exercise Best

JOURNAL: Euro J Clin Nutrition 2003;57;531-542

AUTHORS: Dr. S. Rao

ABSTRACT: Strenuous physical activity by mothers during pregnancy results in small birth size of their offspring, according to a study from India by a multinational team of researchers.

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COMMENTARY: Women from rural areas of India and other developing countries continue to engage in physical activities during pregnancy, both at home and in their farms.

To examine the hypothesis that physical activity during pregnancy may be a "potentially modifiable risk factor" for improving the birth weights, the researchers followed 797 women through their pregnancy.

Trained health workers performed a detailed clinical assessment during their monthly visits and assessed the nutritional intake at 18 weeks and 28 weeks of pregnancy. Physical activity was graded as low, medium and high and scored using a questionnaire, which was administered at around 18 and 28 weeks gestation.

The researchers observed that over two-thirds of the women had performed medium and high levels of activity during pregnancy, including working in their farms, collecting firewood and carrying water.

Moderate and high physical activities at 18 weeks and 28 weeks gestation were associated with lower birth weights, head circumference and mid arm circumference, Dr. S. Rao and colleagues report.

Physical activity at 18 weeks was also associated with lower placental weights, they add. The association was more significant among mothers with pre-pregnant weight less than 45 kilograms, indicating the role of maternal weight in birth size, they explain.

Among the physical activities, "fetching water" was considered the most demanding and had the strongest association with small birth size.

Weight gain during pregnancy was also lowest among mothers with medium and high activity scores at 28 weeks gestation, the investigators note. However, they found that premature deliveries, neonatal length and body fat were not affected by maternal physical activity.

Strenuous physical activity may decrease the placental blood flow resulting in poor fetal growth, Dr. Rao's team postulates. Postures like bending that are adopted while carrying water, may exacerbate the problem, they add.

"Limiting maternal strenuous activities could be a potential intervention for improving birth size," the authors conclude in their paper.

Take home message is to keep your exercise levels moderate and not overdo it.