The relationship between maternal physical activity during pregnancy and birth weight.

INTRODUCTION Earlier studies in India have demonstrated an inverse relationship between physical activity and birth weight in rural women who had high levels of physical activity related to agricultural and domestic activities. There are no data on urban Indian women from a wide range of socio-economic backgrounds with varying levels of physical activity. This study assessed the role of different domains of physical activity during pregnancy and its relation to birth weight. METHODS Data on maternal anthropometry and maternal physical activity level were collected at the 1st trimester (baseline), the 2nd trimester and the 3rd trimester of pregnancy. Birth weight for 546 live born babies was measured immediately after delivery. RESULTS The time spent in sedentary activities (median "cut-off" of 165 min/d) was significantly associated with maternal body weight in the first trimester of pregnancy (51.2 kg vs. 54.1 kg, p < 0.001). Women in the highest tertile of physical activity level in the 1st trimester were 1.58 times (95% CI: 1.02-2.44) more likely of having a baby in the lowest tertile of birth weight with reference to the first tertile. This significant association continued after adjustment for maternal weight and energy intake. CONCLUSION The present study shows that physical activity in the first trimester is associated with low birth weight in Indian babies.