Teratogen update: Lead and pregnancy

Abstract

This review focuses on the impacts of lead exposure on reproductive health and outcomes. High levels of paternal lead exposure (Ͼ40 g/dl or Ͼ25 g/dl for a period of years) appear to reduce fertility and to increase the risks of spontaneous abortion and reduced fetal growth (preterm delivery, low birth weight). Maternal blood lead levels of approximately 10 g/dl have been linked to increased risks of pregnancy hypertension, spontaneous abortion, and reduced offspring neurobehavioral development. Somewhat higher maternal lead levels have been linked to reduced fetal growth. Some studies suggest a link between increased parental lead exposure and congenital malformations, although considerable uncertainty remains regarding the specific malformations and the dose-response relationships. Common methodological weaknesses of studies include potential exposure misclassifications due to the frequent unavailability of exposure biomarker measurements at biologically appropriate times and uncertainty regarding the best exposure biomarker(s) for the various outcomes. A special concern with regard to the pregnant woman is the possibility that a fetus might be exposed to lead mobilized from bone stores as a result of pregnancy-related metabolic changes, making fetal lead exposure the result of exposure to exogenous lead during pregnancy and exposure to endogenous lead accumulated by the woman prior to pregnancy. By reducing bone resorption, increased calcium intake during the second half of pregnancy might reduce the mobilization of lead from bone compartments, even at low blood lead levels. Subgroups of women who incurred substantial exposures to lead prior to pregnancy should be considered to be at increased risk. Birth Defects Research (Part A) 73:409-420, 2005.

Lead Poisoning in an Adult: Lead Mobilization by Pregnancy?

“…28 Adequate calcium supplementation (1,200 mg calcium per day) 29 has been found to be an important means of limiting fetal and maternal lead toxicity especially during the second half of the pregnancy. 2 Lead-induced decreases in birth weight and length are nevertheless unlikely to be prevented. 30 During lactation, however, calcium supplementation is evidently less effective in minimizing the lead mobilization from the skeleton.…”

“…During pregnancy, even lower lead levels are of serious concern because of their adverse effects on the fetus, including developmental delays, low birth weight, and miscarriage. 2,3 Here, we report the case of an adult female who had last been exposed to lead 7 years earlier but now presented with symptoms and findings of acute lead poisoning which we treated with chelation therapy. In the absence of an acute lead exposure, her increased lead levels were likely due to increased mobilization and redistribution from mineralized tissues during and after a recent pregnancy.…”

“…1,2 Especially higher lead levels or exposure over longer periods can cause irreversible damage to the nervous systems and the kidneys. During pregnancy, even lower lead levels are of serious concern because of their adverse effects on the fetus, including developmental delays, low birth weight, and miscarriage.…”

Estimating perchlorate exposure from food and tap water based on US biomonitoring and occurrence data

“…High dose occupational lead exposure, usually with BLLs greater than 40 mg/dL, may alter sperm morphology, reduce sperm count, and decrease fertility (Alexander et al, 1996;Telisman et al, 2000). At low environmental exposures, lead in women may be associated with hypertension during pregnancy, premature delivery, and spontaneous abortion (Baghurst et al, 1987;Bellinger 2005;Borja-Aburto et al, 1999).…”

Lead Exposure in Female Workers Who are Pregnant or of Childbearing Age

“…Although the average blood lead level in both studies was classified as acceptable, several studies have reported adverse pregnancy outcomes occurring at these blood levels or even lower 9,16,64,65) . In addition, some of the subjects in both studies had blood lead levels greater than 20 µ g/dl, suggesting a high risk of adverse pregnancy outcomes [66][67][68] .…”