Maternal prenatal lifestyle factors and infectious disease in early childhood: A follow-up study of hospitalization within a Danish birth cohort

Objectives. To examine whether maternal prenatal lifestyle factors were ass ociated with the risk of hospitalization with infectious disease during ear ly childhood and whether a possible association was modified by fetal growt h reduction. Methods. The study was based on a birth cohort of 10 400 newborns whose mot hers attended the midwife centers in Odense and Aalborg, Denmark, from Apri l 1984 to April 1987 at approximately the 36th week of gestation. Informati on on hospitalization with infectious disease was extracted from the Nation al Hospital Discharge Registry, and newborns were followed up to the end of 1996. Results. Among 6022 children who were hospitalized at least once, 31.4% (n = 1892) were hospitalized with infectious diseases. The cumulative incidenc e rate of hospitalization with infections in children from the age of 6 mon ths to 12 years was 18.9%. The incidence rate ratio in children born to mot hers smoking during pregnancy was 1.24 (95% confidence interval: 1.13-1.36) compared with those of nonsmoking mothers. Mothers whose body mass index w as <18 kg/m(2) were more likely to give birth to infants who were hospitali zed with infectious disease (incidence rate ratio: 1.29; 95% confidence int erval: 1.05-1.59). The increased risk was present in children only up to th e age of 5 years. Conclusions. The study shows that maternal smoking during pregnancy and a l ow prepregnancy body mass index are associated with a higher risk of hospit alization with infectious disease during early childhood. These association s are independent of fetal growth indicators.