['Atopic dermatitis (AD) often develops in infancy as the first manifestation of the atopic phenotype. Wheezing is also common in infancy, but it is less clear whether infant wheezing should be considered as an atopic phenotype. If infant wheeze and AD share a common aetiology, this would indicate that infant wheezing is an atopic phenotype.', 'To investigate whether potential risk factors for infant wheeze and AD have similar effects on these 2 phenotypes, indicating a common etiology.', 'A total of 34.793 mother-child pairs enrolled in the Danish National Birth Cohort were followed prospectively. Information on wheezing episodes, AD, and prenatal, perinatal, and postnatal risk factors was collected by interview at 12 and 30 weeks of gestation, at 6 and 18 months of age, and by linkage to the Danish Medical Birth Register. Data were analyzed by binary and polytomous logistic regression models.', 'The following variables had significantly differential effects on infant wheezing and AD: parental hay fever, parental asthma, parental AD, sex, maternal age, maternal occupation, smoking during pregnancy, season of birth, birth weight, gestational age, head circumference, breast-feeding, number of older siblings, day care attendance, and pets in the home.'] Do differential effects of risk factors on infant wheeze and atopic dermatitis emphasize a different etiology?