The Relationship between Blood and Serum Lead Levels in Peripartum Women and their Respective Umbilical Cords

Abstract

Foetal exposure to lead (Pb) during pregnancy is a major problem. However, no previous study has examined whether Pb concentrations in blood (Pb-B) and in serum (Pb-S) from pregnant women correlate with Pb-B and Pb-S in the foetuses. This hypothesis was tested in the present study. We measured Pb-B and Pb-S in 120 healthy pregnant women (more than 38 weeks of gestation) and their respective umbilical cord samples. The analyses were carried out with an inductively coupled plasma mass spectrometer. We found higher Pb-B levels in the women compared with their respective umbilical cord samples (1.736 € 0.090 lg ⁄ dL and 1.194 € 0.062 lg ⁄ dL, respectively; p < 0.05). In parallel, we found higher Pb-S levels in the women compared with their respective umbilical cord samples (0.042 € 0.003 lg ⁄ dL and 0.032 € 0.003 lg ⁄ dL, respectively; p < 0.05). However, similar %Pb-S ⁄ Pb-B ratios were found in the women compared with their respective umbilical cord samples (2.414 € 0.210% and 2.740 € 0.219%, respectively; p > 0.05). Interestingly, we found positive correlations between Pb-B in the umbilical cords and Pb-B in the respective pregnant women (rs = 0.5714; p < 0.0001), and between Pb-S in the umbilical cords and Pb-S in the respective pregnant women (rs = 0.3902; p < 0.0001) as well as between %Pb-B ⁄ Pb-S in the umbilical cords and %Pb-B ⁄ Pb-S in the respective pregnant women (rs = 0.3767; p < 0.0001). These results indicate that the assessment of Pb-B and Pb-S in pregnant women provides relevant indexes of foetal exposure to Pb. Moreover, the similar %Pb-S ⁄ Pb-B in pregnant women and in the umbilical cords shows that the foetuses are directly exposed to the rapidly exchangeable Pb fraction found in their mothers.Major concerns exist with regard to lead (Pb) exposure, which should not be found in the blood, especially during pregnancy. For example, lead exposure may affect and disrupt normal physiology as well as increase the oxidative stress [1]. The increased demands for calcium during pregnancy lead to increased bone turnover and increased circulating Pb levels [2,3]. Pb from the mother can easily cross the placenta [4] and expose the foetus to the harmful effects of Pb, thus affecting the embryonic development of multiple organ systems and causing retardation of cognitive development [5]. Indeed, recent results have indicated reduced intellectual development in children with a history of prenatal lead exposure [6].Because Pb accumulates in bone and has a half-life of years or decades, Pb transference to the foetus may take place even years after maternal exposure [3,7]. In order to study the impact of prenatal exposure to Pb, the concentrations of this metal are usually measured in maternal whole blood (Pb-B) [8][9][10]. Others have measured prenatal maternal bone Pb levels as an index of Pb burden [3,11]. However, it is not clear which is the best biomarker to assess lead exposure during pregnancy. It is possible that serum (Pb-S) or plasma (Pb-P) Pb concentrations may be better indexes of Pb exposur...

Changes in low levels of lead over the course of pregnancy and the association with birth outcomes

“…We found a statistically significant association at each time point. Previous studies of women with higher blood lead have yielded similar results [30,33,34] with observed correlations between cord and maternal blood lead of r 2 = .57 and r 2 = .63 [34]. Those correlation values are within a reasonable range of the correlations observed in the present study for the second and third trimesters (r 2 = .74 and r 2 = .83, data not shown).…”

The relationship between blood lead levels and occupational exposure in a pregnant population

“…Lead can cross the placenta and expose the fetus to the harmful effects of this toxic, thus affecting the embryonic development of multiple organs and causing neurobehavioral impairments in infancy and early childhood [4, 5, 9, 17]. Therefore, pregnancy is considered a critical time for exposure to lead for the mother and the fetus [14, 18]. …”

Adverse effects of maternal lead levels on birth outcomes in the ALSPAC study: a prospective birth cohort study

“…Lead readily crosses the placenta, with a fetal : maternal ratio of about 0.7–0.9,4–6 but studies on the association of blood lead levels in pregnancy and a variety of measures of birth outcomes, including birthweight (BW), head circumference (HC), gestational age at delivery and preterm delivery, have had inconsistent results at all levels of exposure 7–11. Poor birth outcomes are known to be associated with poor developmental trajectories in infancy, as well as having long-term implications for adult health 12–14.…”