Decrease in Birth Weight in Relation to Maternal Bone-Lead Burden

Department of Environmental Health , Harvard University, Cambridge, Massachusetts, United States
PEDIATRICS (Impact Factor: 5.47). 12/1997; 100(5):856-62. DOI: 10.1542/peds.100.5.856
Source: PubMed


Birth weight predicts infant survival, growth, and development. Previous research suggests that low levels of fetal lead exposure, as estimated by umbilical cord blood-lead levels at birth, may have an adverse effect on birth weight. This report examines the relationship of lead levels in cord blood and maternal bone to birth weight.
Umbilical cord and maternal venous blood samples and anthropometric and sociodemographic data were obtained at delivery and 1-month postpartum. Blood-lead levels were analyzed by atomic absorption spectrophotometry. Maternal tibia and patella lead levels were determined at 1-month postpartum with use of a spot-source 109Cd K-X-ray fluorescence instrument. The relationship between birth weight and lead burden was evaluated by multiple regression with control of known determinants of size at birth.
Data on all variables of interest were obtained for 272 mother-infant pairs. After adjustment for other determinants of birth weight, tibia lead was the only lead biomarker clearly related to birth weight. The decline in birth weight associated to increments in tibia lead was nonlinear and accelerated at the highest tibia lead quartile. In the upper quartile, neonates were on average, 156 grams lighter than those in the lowest quartile. Other significant birth weight predictors included maternal nutritional status, parity, education, gestational age, and smoking during pregnancy.
Our results indicate that bone-lead burden is inversely related to birth weight. Taken together with other research indicating that lead can mobilize from bone into plasma without detectable changes in whole blood lead, these findings suggest that bone lead might be a better biomarker than blood lead. Because lead remains in bone for years to decades, mobilization of bone lead during pregnancy may pose a significant fetal exposure with health consequences, long after maternal external lead exposure has declined.

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Available from: Howard Hu, Sep 19, 2014
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    • "Exposure to heavy metals in women and men of reproductive ages is an issue of current concern, since the evidence is rising that even low levels of exposure to these compounds can affect fetal growth and development [53,54]. Exposure to maternal lead during pregnancy has been proposed as a risk factor for reduced fetal growth [55,56]. However, studies estimating newborn’s exposure through cord blood [53,57-59] have found contradictory results, suggesting that the possible effects of this metal on newborn’s health could depend on the dose [60] or on the timing of exposure [61]. "
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    ABSTRACT: In Spain, few studies have evaluated prenatal exposure to heavy metals. The objective of this study was to describe lead, mercury and cadmium concentrations in blood from a sample of newborn--mother-father trios, as well as to investigate the association between metals in cord blood and parental variables. We also explored the relationship between cord blood metal concentrations and child characteristics at birth. Metal correlations among family members were assessed using Spearman Rank Correlation Coefficient. Linear regression was used to explore the association between parental variables and log-transformed cord blood lead and cord blood mercury concentrations. In the case of cadmium, tobit regression was used due to the existence of samples below the detection limit. The association between cord blood metal concentrations and child characteristics at birth was evaluated using linear regression. Geometric means for lead, mercury and cadmium were 14.09 mug/L, 6.72 mug/L and 0.27 mug/L in newborns; 19.80 mug/L, 3.90 mug/L and 0.53 mug/L in pregnant women; and 33.00 mug/L, 5.38 mug/L and 0.49 mug/L in men. Positive correlations were found between metal concentrations among members of the trio. Lead and cadmium concentrations were 15% and 22% higher in newborns from mothers who smoked during pregnancy, while mercury concentrations were 25% higher in newborns from mothers with greater fish intake. Cord-blood lead levels showed seasonal periodicity, with lower concentrations observed in winter. Cord blood cadmium concentrations over 0.29 mug/L were associated with lower 1-minute and 5-minute Apgar scores. These results reinforce the need to establish biomonitoring programs in Spain, and provide support for tobacco smoke and fish consumption as important preventable sources of heavy metal exposure in newborns. Additionally, our findings support the hypothesis that cadmium exposure might be deleterious to fetal development.
    Full-text · Article · Sep 2013 · BMC Public Health
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    • "Recent studies pointed to the toxic effects of lead, mainly associated with the most rapidly exchangeable fraction (the plasma fraction) which is associated with the harmful effects of Pb [50, 51]. Although 99 % of lead in whole blood is bound to red blood cells, only lead that is available to cross the placenta is derived from lead that is in the free-state in plasma [5, 26, 51]. Chuang et al. [5] showed that exposure to lead in the air, including cigarette smoke, significantly affects its level in the plasma, without affecting its concentration in whole blood. "
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    ABSTRACT: To assess the effect of lead exposure from cigarette smoke on fetal growth, blood lead concentrations were measured using inductively coupled plasma mass spectrometry in 150 healthy pregnant women. Mean lead concentrations in plasma and whole blood were significantly higher in the smoking group compared with the nonsmoking group in each trimester of pregnancy (p < 0.001). Logistic regression analysis showed the highest impact of the number of cigarettes smoked per day for serum lead concentration (β = 0.238; p < 0.05), while in whole blood, it was duration of smoking before conception (β = 0.297; p < 0.001). Birth weight of the smoking mothers' infants was significantly lower (mean ± SEM, 3,192 ± 50.8 and 3,569 ± 49.6 g, respectively; p < 0.001) and negatively correlated with lead levels in plasma (r = -0.38; p < 0.001) and in whole blood (r = -0.27; p < 0.001). Therefore, it is suggested that smoking during pregnancy increases lead concentrations in maternal blood. Fetal exposure to low doses of lead in utero may be a serious risk factor causing lower birth weight.
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    • "There is some evidence that also prenatal cadmium exposure adversely affects children’s IQ [11]. Furthermore, it has been reported that prenatal exposure to lead and cadmium is associated with reduced birth weight, birth length and head circumference [11] [12] [13] [14] [15] [16] [17] [18]. It appears that mercury does not affect intrauterine growth [19] [20], nonetheless, an increased risk for preterm delivery has been reported [21]. "
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    ABSTRACT: The heavy metals mercury, lead, and cadmium are toxicants, which are well-known to cross the placenta and to accumulate in fetal tissues. Prenatal exposure to mercury and lead poses a health threat particularly to the developing brain. Fetal exposures to lead and cadmium correlate with reduced birth weight and birth size. The placental passage of cadmium is limited suggesting a partial barrier for this metal. It is very likely that metallothionein is responsible for placental storage of the metals especially of cadmium. It is unclear, however, which proteins are involved in placental uptake and efflux of the metals and where the transporters are located at the placental barrier. Hence, only certain aspects of placental metal toxicokinetics are known so far. The metals have also been shown to adversely affect placental functions. Both metal-specific placental transfer and impairment of placental function can explain the relationships between prenatal metal exposures and adverse effects on intrauterine growth and (neuro)development.
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