Not Exposed (n=910), n/N* (%) Exposed (n=1216), n/N* (%)
Sex (boys) 462/886 (52.1) 656/1216
Gestational age at birth (weeks) 39.08\(\pm\)1.25 39.21\(\pm\)1.21
Maternal education level††
Highschool graduation 27/887 (3.0) 80/1215 (6.6)
College/University 631/887 (71.1) 890/1215 (73.3)
Graduate school 229/887 (25.8) 245/1215 (20.2)
Maternal age at birth (years) 33.62\(\pm\)3.58 32.96\(\pm\)3.46
Mode of delivery
Vaginal 543/885 (62.8) 768/1211 (63.4)
Cesarean 342/885 (38.6) 443/1211 (36.6)
Feeding type until 6 months
Breastmilk only 152/864 (17.6) 218/1176 (18.5)
Formula and Breastmilk 712/864 (82.4) 958/1176 (81.5)
Parental history of allergic disease (yes) 473/895 (52.8) 632/1208 (52.3)
SHS exposure during the first year of life (yes) 123/837 (14.7) 443/1129 (39.2)
Daycare attendance during the first year of life (yes) 173/839 (20.6) 265/1130 (23.5)
Pet exposure during the first year of life (yes) 37/840 (4.4) 74/1130 (6.5)
Values are frequency (%). SHS, Secondhand smoke exposure. * n, the number of children with each characteristic; N, the total number of children with information available on this characteristic. **Fisher’s exact. †χ2 test for proportions, Student’s t-test for mean. Values are frequency (%). SHS, Secondhand smoke exposure. * n, the number of children with each characteristic; N, the total number of children with information available on this characteristic. **Fisher’s exact. †χ2 test for proportions, Student’s t-test for mean. Values are frequency (%). SHS, Secondhand smoke exposure. * n, the number of children with each characteristic; N, the total number of children with information available on this characteristic. **Fisher’s exact. †χ2 test for proportions, Student’s t-test for mean.