Maternal Blood Levels of Toxic and Essential Elements and Birth Outcomes in Argentina: The EMASAR Study

Abstract

Pregnant women's levels of toxic and essential minerals have been linked to birth outcomes yet have not been adequately investigated in South America. In Argentina, n = 696 maternal whole blood samples from Ushuaia (n = 198) and Salta (n = 498) were collected in 2011-2012 among singleton women at 36 ± 12 h postpartum and analyzed for blood concentrations of arsenic (As), cadmium (Cd), mercury (Hg), lead (Pb), copper (Cu), manganese (Mn), selenium (Se) and zinc (Zn). This study examined the associations between maternal elements levels and birth outcomes, and sociodemographic factors contributing to elements levels. Maternal age, parity, body mass index, smoking, and education were linked to concentrations of some but not all elements. In adjusted models, one ln-unit increase in Pb levels was associated with increased gestational age (0.2 weeks, 95% CI = 0.01-0.48) and decreased birth weight (-88.90 g, 95% CI = -173.69 to -4.11) and birth length (-0.46 cm, 95% CI = -0.85 to -0.08) in the Salta sample. Toxic elements concentrations were not associated with birth outcomes in Ushuaia participants. Birth outcomes are multifactorial problems, and these findings provide a foundation for understanding how the body burden of toxic and essential elements, within the socioeconomic context, may influence birth outcomes.

Keywords: biomonitoring; children’s environmental health; environmental exposures; social determinants of health; toxic metals.

Figure 1

Relative change (%) in geometric mean of maternal whole blood concentrations (µg/L) of essential and toxic elements by unit change calculated from coefficients β and standard errors of the multiple linear regression analyses described in Supplementary Materials, Table S2. The unit of change for each variable was set as interquartile range. ^a Salta as reference site (Salta vs. Ushuaia); ^b para 1 as reference category (para 1 vs. parous); ^c non-smokers as reference (non-smoker vs. smoker); ^d the highest education level is primary or secondary as the reference group (primary/secondary education vs. tertiary/university); and ^e urban dweller as reference category (urban vs. semi-urban and rural). Abbreviations: As, arsenic; BMI, body mass index; Cd, cadmium; Cu, copper; Hg, mercury; Mn, manganese; Pb, lead; Se, selenium; and Zn, zinc.

Figure 2

Changes in the birth outcomes associated with overall and regional specific blood elements concentrations (A-1,B-1,C,D). The results of logistic regression analyses show the relationships between tertile of maternal elements levels and preterm birth and low birth weight (A-2,B-2). The elements concentrations were natural logarithms transformed. Effect estimates presented as changes in the gestational age, birth weight, length, and head circumference for one ln-unit change in the elements. The odds ratios of the logistic regression analyses are displayed with 95% confidence interval, with the first tertile of the elements levels as the reference. All models were adjusted for maternal age, parity, pre-pregnancy BMI, smoking, and education. In addition, birth weight and birth length were added into the gestational age regression model (A-1), and gestational age was introduced into the birth weight (B-1), length (C), and head circumference (D) regression models. Low birth weight was introduced into preterm birth (A-2) and preterm birth was introduced into low birth weight model (B-2). Abbreviations: As, arsenic; Cd, cadmium; Cu, copper; Hg, mercury; Mn, manganese; Pb, lead; Se, selenium; and Zn, zinc.

Figure 3

Interaction effects of infant sex on the association between average maternal Cu concentration and gestational age and birth length; and the relationship between average maternal Zn level and gestational age. Models (A-1,A-2) were adjusted for maternal age, parity, pre-pregnancy BMI, smoking, education, birth weight, and birth length. Model (B) was adjusted for maternal age, parity, pre-pregnancy BMI, smoking, education, and gestational age. Abbreviations: Cu, copper; Zn, zinc.