Table 1

Distribution of risk factors

No. %
Maternal smoking during third trimester
 None7169(83.7)
 1 to 9 cigarettes per day575(6.7)
 10 to 19 cigarettes per day618(7.2)
 20 or more cigarettes per day199(2.3)
Environmental tobacco smoke exposure
 Never5545(64.8)
 <1 hour per day1548(18.1)
 1 to 2 hours563(6.6)
 2 to 4 hours439(5.1)
 4 hours or more312(3.6)
 “Always”154(1.8)
Maternal history of asthma933(11.1)
Preterm delivery356(4.2)
Male sex4447(51.9)
Living in rented accommodation1598(19.0)
Damp in home
 None4402(52.4)
 Not serious3597(42.8)
 Fairly serious336(4.0)
 Very serious61(0.7)
Mould in home
 None6675(80.0)
 Not serious1454(17.4)
 Fairly serious183(4.0)
 Very serious33(0.7)
Number of children in home
 None3779(44.5)
 13165(37.2)
 21184(13.9)
 3287(3.4)
 ⩾484(1.0)
Number of previous pregnancies
 None2878(34.1)
 12829(33.5)
 2 1531(18.1)
 3742(8.8)
 4274(3.2)
 ⩾5196(2.3)
Single marital status of mother1625(19.2)
Duration of breast feeding (n = 8358)
 None1835(22.0)
 Up to 1 month1233(14.8)
 Between 1 and 3 completed months1419(17.0)
 Between 3 and 6 completed months1113(13.3)
 6 or more completed months2758(33.0)