Influence of heavy agricultural work during pregnancy on birthweight in northeast Brazil.

BACKGROUND Women in developing countries often continue their agricultural work during late pregnancy. Whether this adversely affects birthweight is not clear from previous studies as few controlled for confounding factors. This study seeks to clarify this issue. METHODS This retrospective cohort study investigated 958 low-income women and their singleton newborn babies residing in a region of Northeast Brazil dependent on sugar-cane production. Women were recruited at maternity centres, when attending for delivery, and were allocated to one of two groups according to their exposure to heavy agricultural labour for at least 3 months during the second and third trimesters of pregnancy (n = 250), or to household activities only (n = 708). RESULTS The mean birthweight of infants born to women who worked in agriculture during 9 months of pregnancy was 190 g lower than that of the non-exposed group (P = 0.02). After controlling for confounding factors, the adjusted effect was 117 g (P = 0.05). Heavy agricultural work for 6, 7 or 8 months had no significant effect. CONCLUSIONS These findings suggest that working throughout pregnancy significantly reduces birthweight in this low-income population.