Women's physical activity and pregnancy outcome: a longitudinal analysis from the Philippines

We assessed the effects of physical activity on pregnancy outcome in 2741 Filipino women identified during pregnancy as part of a two-year longitudinal study. Specific elements of physical activity hypothesized to be relevant to pregnancy outcome were posture, energy expenditure, and physical stress. Variables were developed for nine household and 48 formal and informal economic activities. Analyses were stratified by whether the woman performed formal waged work outside of the home, income-related activity at home, or was economically inactive. Results show that traditional definitions of physical activity and work based on participation in the formal labour force ignore a sizeable amount of home economic production, as well as the physical demands of housework. We saw no difference in risk of low birthweight or preterm delivery in economically active compared to economically inactive women. However, we found that increased amounts of standing activity affected pregnancy outcome in certain groups of women. Accurate assessment of the effects of physical activity during pregnancy must examine specific components of the activity, rather than relying on formal employment as a proxy for exposure.