Prenatal factors and use of anti-asthma medications in early childhood: a population-based Danish birth cohort study.

To examine whether fetal growth indicators and other prenatal factors were associated with the use of anti-asthma medications during the first year of life, we conducted a follow-up study based on birth registry and prescription registry data of the county of North Jutland, Denmark. We identified 9705 singletons born between 1 April 1996 and 31 December 1997. They were followed to the end of the first year of life by linkage with a prescription registry. Prescription for asthma was defined as both a beta-agonist and an inhaled glucocorticoid prescription. A prescription for asthma was presented to 3.8% of the infants during the first year of life. Maternal asthma, male gender, maternal smoking, multiparous births, young maternal age, and maternal non-cohabitation were associated with the risk of receiving a prescription for asthma. There were slightly increased trends in the risk with birth weight and placental weight. The increased risk was more pronounced in the groups of birth weight > or = 3800 g (adjusted OR: 1.23, 95% CI: 0.88-1.73) and placental weight > or = 750 g (adjusted OR: 1.44, 95% CI: 1.10-1.88). The increased risk was also associated with a high ponderal index of > or = 2.7 g/cm3 (adjusted OR: 1.37, 95% CI: 1.06-1.76).