It appears that blood levels of some pollutants in women may drop by nearly half during pregnancy,8 in part because their bodies pass them off through the placenta.9 That may be why breast milk concentrations of pollutants appear higher after the first pregnancy than in subsequent ones.10 This could explain why birth order was found to be a significant predictor of pollutant levels in young people. Basically, firstborn kids may get first dibs on mom’s store of toxic waste, leaving less for their baby brothers and sisters.
