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 n ot clear from previous studies as few controlled for confounding factors. T his study seeks to clarify this issue. Methods This retrospective cohort study investigated 958 low-income women a nd their singleton newborn babies residing in a region of Northeast Brazil dependent on sugar-cane production. Women were recruited at maternity centr es, when attending for delivery, and were allocated to one of two groups ac cording to their exposure to heavy agricultural labour for at least 3 month s during the second and third trimesters of pregnancy (n = 250), or to hous ehold activities only (n = 708). Results The mean birthweight of infants born to women who worked in agricul ture during 9 months of pregnancy was 190 g lower than that of the non-expo sed group (P = 0.02). After controlling for confounding factors, the adjust ed effect was 117 g (P = 0.05). Heavy agricultural work for 6, 7 or 8 month s had no significant effect. Conclusions These findings suggest that working throughout pregnancy signif icantly reduces birthweight in this low-income population.