Effect of psychosocial stress and physical activity on low birthweight: a cohort study

To determine the effect of physical activity and psychosocial stress on low birthweight (LBW).

A prospective study was carried out in a district of Sri Lanka between May 2001 and April 2002. A total of 885 pregnant mothers were recruited at < or = 16 weeks of gestation and followed up until partus. Trimester-specific exposure statuses along with potential confounding factors were gathered on average at the 12th, 28th, and 36th weeks of gestation. Physical activities were assessed by inquiring about the duration of specific postures adopted per day by housewives during each trimester at home and both at home and during working hours for those who were engaged in paid employment. Psychosocial stress was assessed using the Modified Life Events Inventory and the General Health Questionnaire 30. LBW was defined as a birthweight of less than 2500 g. Multiple logistic regression analysis was applied for controlling confounders and the results were expressed as adjusted odds ratios (OR) and 95% confidence intervals (95%CI).

Standing > 2.5 h/day (OR 2.26; 95%CI 1.10, 4.69) during the second trimester and sleeping 8 h or less/day (OR 2.84; 95%CI 1.49, 5.40) either during the second, third or both trimesters together, an increase in maternal age in years (OR 0.92; 95%CI 0.87, 0.98), and body mass index < 19.8 kg/m(2) (OR 2.2; 95%CI 1.17, 4.22) had a statistically significant association with LBW. Psychosocial stress was not associated with LBW.

Standing > 2.5 h/day and sleeping < or = 8 h/day were risk factors for LBW, whereas psychosocial stress was not.