I think this topic is important and worth spending some more time on, so here goes:
Lead has a half life of 25 years, so it stays around a long time. Your body stores lead in the bones, brain, and teeth. For women, this means that when we are exposed to lead as children, we then expose our children during pregnancy. Pregnancy causes bone loss which releases stored lead back into the bloodstream where it crosses the placenta to the growing baby. A study comparing maternal blood levels during each trimester of pregnancy with cognitive development of the child for the first two years of life concluded that fetal lead exposure does have a negative impact on the neurological development of the child and lead exposure during the first trimester seems to have the most impact.
This is certainly scary information for anyone thinking of having children. There are steps you can take to protect your baby. Calcium prevents bone loss, but you need to up your calcium intake before you get pregnant if possible to protect your baby during the most vulnerable window. You can take a calcium supplement or pay special attention to consuming natural sources of calcium. If you are vegan or don't consume dairy, you can eat kale, blackstrap molasses, collard greens, and turnip greens.(For a longer list of calcium rich foods, please see the resources.) You can also have your blood lead level checked before and during pregnancy. Be sure to talk to your practitioner if you have questions or concerns about your lead level during pregnancy.
Resources:
http://www.vrg.org/nutrition/calcium.htm
http://leadonthebrain.blogspot.com/2012/02/lead-in-breast-milk-and-during.html
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1665421/
