Genetic modification of the effect of maternal household air pollution exposure on birth weight in Guatemalan newborns

• GSTM1 and GSTT1 genes may modify the association between maternal exposure to wood smoke and birth weight.
• Maternal null GSTM1 was associated with a 144 g (95% CI, −291, 1) decrease in birth weight.
• Combined maternal/infant null GSTT1 was associated with a 155 g (95% CI, −303, −8) decrease in birth weight.
• Effect modification by chimney stove use was not demonstrated.

Low birth weight is associated with exposure to air pollution during pregnancy. The purpose of this study was to evaluate whether null polymorphisms of Glutathione S-transferases (GSTs), specifically GSTM1 and GSTT1 genes in infants or mothers, modify the association between high exposures to household air pollution (HAP) from cooking fires and birth weight. Pregnant women in rural Guatemala were randomized to receive a chimney stove or continue to use open fires for cooking. Newborns were measured within 48 h of birth. 132 mother–infant pairs provided infant genotypes (n = 130) and/or maternal genotypes (n = 116). Maternal null GSTM1 was associated with a 144 g (95% CI, −291, 1) and combined maternal/infant null GSTT1 was associated with a 155 g (95% CI, −303, −8) decrease in birth weight. Although there was a trend toward higher birth weights with increasing number of expressed GST genes, the effect modification by chimney stove use was not demonstrated.