Assessment of Maternal–Neonatal Transplacental Passage of Heavy Metals in Enugu, Nigeria

Abstract

Background: Prenatal exposure to heavy metals leads to cognitive deficits, preterm birth, low birth weight, lower IQ, and increased risk of respiratory disorders. Heavy metals impair neonatal health by causing oxidative stress, damaging developing organs, and disrupting neurodevelopment.

Objectives: To determine the maternal and cord serum concentrations of toxic/heavy metals and its effect on neonatal health.

Materials and Methods: Maternal and cord blood samples were collected immediately after delivery into a plain vacutainer. Heavy metals - lead (Pb), arsenic (As), mercury (Hg), and cadmium (Cd) - were assayed using Atomic Absorption Spectrometer (AAS). The infants were given APGAR test between one and five minutes after birth to evaluate their appearance, heart rate, grimace, activity, and respiration.

Results: Neonatal outcomes showed mean gestational age of 39.94 ± 0.31 weeks, birth weight of 3.21 ± 0.46 kg, APGAR score of 7.86 ± 0.50 and Maternal serum levels of As (10.07 ± 11.07 µg/dl), Cd (19.40 ± 18.52 µg/dl), Pb (30.21 ± 25.94 µg/dl), and Hg (10.41 ± 11.54 µg/dl) were significantly higher (P < 0.001) than corresponding cord serum levels and exceeded recommended safety limits. Positive and significant correlations were observed between maternal and cord serum metal levels, particularly for Pb (r = 0.851, P < 0.001) and Hg (r = 0.561, P < 0.001). Correlation analysis revealed significant negative association between maternal age and mercury levels (r = −0.192, P = 0.020).

Conclusion: The findings demonstrate that maternal heavy metal load predicts fetal exposure despite lower cord concentrations, highlighting fetal vulnerability.