TABLE 1

Characteristics of Children Who Swam as Infants and Their Controls

Swimming Infants (N = 43)Other Children (N = 298)P
Age, mean (SD), ya11.5 (0.6)11.5 (0.6).98
Boys, n (%)b22 (51.1)150 (50.3).92
White, n (%)b35 (81.4)228 (76.5).48
BMI, mean (SD), kg/m2a18.5 (2.7)18.4 (2.5).81
Mother and/or father with asthma, n (%)b6 (14.0)58 (19.5).39
Mother and/or father with hay fever, n (%)b13 (30.2)87 (29.2).89
Birth weight, mean (SD), kga3.19 (0.57)3.34 (0.54).96
No. of siblings, mean (SD)a2.56 (1.30)2.68 (1.28).56
Housing density, mean (SD), persons per rooma0.83 (0.36)0.79 (0.30).36
Breastfeeding, n (%)b9 (20.9)34 (11.4).21
Exposure to pets since birth, n (%)b9 (20.9)47 (15.8).39
Child care attendance n (%)b24 (55.8)151 (50.7).40
Passive smoking at home, n (%)b18 (41.8)72 (24.2).014
Maternal smoking during pregnancy, n (%)b16 (37.2)46 (15.4).0005
Backyard pool, n (%)b6 (14.0)9 (3.0).0011
Cumulated indoor pool attendance, median (interquartile range), hc146 (88–281)83 (42–182).0002
  • a By 2-sided unpaired t test.

  • b By χ2 test.

  • c By 2-sided Mann-Whitney U test.