TABLE 1.

Participant characteristics

Characteristics	n	(%)
Sex	3089
Boy	1576	(51.0)
Girl	1513	(49.0)
Asthma incidence	2934
Age 0–12 months	78	(2.7)
Age 12–24 months	140	(4.8)
Age 24–36 months	88	(3.0)
Age 0–36 months	306	(10.4)
None	2628	(89.6)
Wheezing incidence	2934
Age 0–12 months	586	(20.0)
Age 12–24 months	398	(13.6)
Age 24–36 months	134	(4.6)
Age 0–36 months	1118	(38.1)
None	1816	(61.9)
Total serum IgE level in 2‐year‐old children	2900
High: ≥180 IU/ml	282	(9.7)
Low: <180 IU/ml	2618	(90.3)
Total serum IgE level during pregnancy	3089
High: ≥214 IU/ml	557	(18.0)
Low: <214 IU/ml	2532	(82.0)
Urinary cotinine level in mid‐pregnancy	3089
>36.8 μg/g‐creatinine	175	(5.7)
0.31–36.8 μg/g‐creatinine	1022	(33.1)
<0.31 μg/g‐creatinine	1892	(61.2)
Passive smoke after birth	3089
Yes	863	(27.9)
No	2226	(72.1)
Presence of indoor pets	3089
Yes	543	(17.6)
No	2546	(82.4)
Lower respiratory tract inflammation	3089
Yes	471	(15.2)
No	2618	(84.8)
Respiratory syncytial virus infection	3089
Yes	606	(19.6)
No	2483	(80.4)
Area	3089
Cold area	1025	(33.2)
Warm low‐humidity area	1202	(38.9)
Warm high‐humidity area	862	(27.9)