Characteristic Category n/N %
Season of birth October to January 224/631 35.5
February to April 169/631 26.8
May to July 145/631 23.0
August to September 93/631 14.7
Sex Female 324/631 51.3
Male 307/631 48.7
Highest parental education Low (<10 years) 15/631 2.4
Medium (=10 years) 268/631 42.5
High (>10 years) 348/631 55.2
Parental atopy No 342/631 54.2
Yes 289/631 45.8
Older siblings No 416/631 65.9
Yes 215/631 34.1
Smoking during pregnancy No 514/612 84.0
Yes 98/612 16.0
Smoking at home between birth and 4 years Never 318/629 50.6
Likely never 56/629 8.9
Ever 255/629 40.5
Exclusive breastfeeding first 4 months No 262/619 42.3
Yes 357/619 57.7
Birth weight (grams) Mean and SD 3509.0 453.9
Changed place of residence between birth and 2 years No 471/631 74.6
Yes 160/631 25.4