Birth weight has been linked to late-onset diseases, including type 1 diabetes (T1D) in the offspring. The aim was to explore pre-natal determinants of birth weight in children carrying HLA-DR-DQ genotypes (DQ2/8; DQ8/8; DQ4/8 AND DQ2/2) conferring high-risk for T1D. Newborns carrying high-risk T1D HLA genotypes were enrolled in Finland, Germany, Sweden and the US. Maternal characteristics during pregnancy were obtained by questionnaire from 6,795 non-diabetic mothers of singleton newborns, 3-4.5 months after delivery. General linear models were used to model the effects of gestational infections, smoking during pregnancy, maternal post-pregnancy height and weight, mother’s age at birth, child’s gender, gestational age and country.
Smoking was associated with the well-known decrease in birth weight. However, gestational upper respiratory tract infection was associated with an increased birth weight (p=0.008) provided that the mother did not smoke. Additionally, gestational upper respiratory tract infection was associated with a reduced birth length but only in smoking mothers (p=0.0006). In contrast, gestational skin infection or rash was associated with lower birth weight regardless of smoking (p=0.036). Studies are in progress to test whether reported gestational infections are associated with the risk for islet autoimmunity i.e. autoantibodies against insulin, GAD65 or IA-2, clinical onset of T1D, or both.
Gestational infections, especially upper respiratory tract infection, had different influence on infant’s birth size, depending on whether or not mothers smoked during pregnancy. Smoking may interact with gestational infections to affect birth size in children at increased genetic risk for T1D.
Funded by NIH, NIDDK, NIAID, NICHD, NIEHS, JDRF and CDC.