Association between maternal serum zinc and birth weight is modified by neonatal SOD2 polymorphism and promoter methylation.

Background: Conflicting findings exist regarding the association between maternal serum zinc and neonatal birth weight. This study aimed to explore the association between maternal serum zinc and birth weight, and whether this association was modified by neonatal SOD2 polymorphism and promoter methylation.

Methods: We recruited 464 mother-newborn pairs at Houzhai Center Hospital from January 2010 to January 2012. Maternal serum zinc concentration was determined using atomic absorption spectrophotometry. Neonatal SOD2 polymorphism and promoter methylation were measured by TaqMan probe assay and real-time quantitative methylation-specific PCR (QMSP), respectively. Relationships among maternal serum zinc, neonatal SOD2 promoter methylation, and birth weight were analyzed by generalized linear model (GLM). Stratified and interaction analyses were conducted to explore the modification of neonatal SOD2 polymorphism and promoter methylation on the association between maternal serum zinc and birth weight.

Results: Our findings revealed that higher maternal zinc concentrations were associated with decreased birth weight (P-trend < 0.05). Each 1 μmol/L increment in maternal zinc level was associated with a 9.553 g (95 % CI: -16.370, -2.735) decrease in birth weight. A significant interaction between SOD2 promoter methylation and maternal serum zinc in relation to birth weight was observed in the AG+GG group (P-interaction < 0.05). Newborns carrying AA genotype were more sensitive to maternal serum zinc in the lower SOD2 group (P-interaction < 0.05).

Conclusions: Maternal serum zinc was inversely associated with birth weight, and this association was modified by neonatal SOD2 polymorphism and promoter methylation. These findings suggest that SOD2 polymorphism and promoter methylation may influence the relationship between maternal zinc status and fetal growth.