Effect of maternal lead burden on infant weight and weight gain at one month of age among breastfed infants

Introduction. Transfer of lead from bone to the bloodstream increases durin g lactation. However, the effect of maternal lead burden on growth in breas tfed newborns is still unknown. This study examined early postnatal growth in a cohort of healthy breastfed newborns in relation to maternal bone lead burden. Methods. Lead levels were measured among 329 mother-infant pairs in umbilic al cord blood at birth and in maternal and infant venous blood at 1 month p ostpartum. Maternal evaluations at 1 month postpartum included lead measure s in blood and bone (measured in the tibia and the patella). Blood lead was determined by graphite furnace atomic absorption spectrophotometry. Bone l ead was measured by Cd-109 Kx-radiograph fluorescence instrument. The prima ry endpoints were attained weight 1 month of age, and weight gain from birt h to 1 month of age, which were analyzed in relation to lead biomarkers and relevant covariates by linear regression models. Results. Infants studied had an average weight gain of 33.1 g/day (standard deviation [SD] = 11.6). Mean infant (at 1 month of age) and maternal blood lead levels were 5.6 mug/dL (SD = 3.0) and 9.7 mug/dL (SD = 4.1), respecti vely. Mean maternal bone lead levels were 10.1 mug of lead/g (SD = 10.3) an d 15.29 mug of lead/g (SD = 15.2) of bone mineral for tibia and patella, re spectively. Infant blood lead levels were inversely associated with weight gain, with an estimated decline of 15.1 g per mug/dL of blood lead. Childre n who were exclusively breastfed had significantly higher weight gains; how ever, this gain decreased significantly with increasing levels of patella l ead. The multivariate regression analysis predicted a 3.6-g decrease in wei ght at 1 month of age per mug of lead per gram bone mineral increase in mat ernal patella lead levels. Conclusions. Maternal lead burden is negatively associated to infant attain ed weight at 1 month of age and to postnatal weight gain from birth to 1 mo nth of age. Additional studies are needed to better understand this source of exposure and to develop interventions to minimize its impact.