Prenatal lead exposure modifies the association of maternal self-esteem with child adaptive ability

A child's adaptive ability is important for personal career and social development. Maternal self-esteem may help shape a child's behavior. This study aims to investigate whether maternal self-esteem measured when their children were toddlers predicts their children's adaptive skills at school age, and whether prenatal lead exposure modifies such a relationship.

We assessed prenatal lead exposure using cord blood lead and maternal bone lead around delivery (tibia and patella lead measured in vivo by K-x-ray-fluorescence) among 192 mother-child pairs investigated in Mexico from 1994 to 2011. Maternal self-esteem was measured using the Coopersmith-Self-esteem-Inventory when children were 2 years old. When children were 7-to-15 years old, we measured children's blood lead levels and administered the 2nd edition of Behavior-Assessment-System-for-Children (BASC-2) parent-rating-scales (PRS) and Self-Reports of Personality (SRP) to evaluate children's adaptive skills.

Median (P25, P75) values for maternal patella and tibia lead, cord blood lead and children's current blood lead levels were 12.6 (3.2, 21.7) μg/g, 10.2 (4.1, 16.0) μg/g, 5.5 (3.5, 8.1) μg/dL and 2.7 (2.0, 4.0) μg/dL, respectively. In adjusted models, increased maternal self-esteem was associated with increased adaptive T-scores on the BASC-2 PRS and SRP scales. This relationship was weaker in high prenatal lead-exposure groups (high cord blood lead or patella lead groups, P25P100) compared with low prenatal lead-exposure (low cord blood lead or patella lead groups, P1P25) groups (P-interaction values < 0.10). No significant interactions between maternal tibia lead and self-esteem on children's adaptive T-scores were observed (P-interaction values > 0.10).

Toddlers of mothers with high (vs. low) self-esteem have better adaptive abilities when they are of school-age. Prenatal lead exposure may attenuate or eliminate this positive association.