Table 1

Observed and imputed characteristics of mothers and children (n=4435)

Data missing (%)Observed datasetImputed dataset
Maternal characteristics
 Age at enrolment (years)0.031.4 (4.7)31.4 (4.7)
 Pre-pregnancy body mass index (kg/m2)9.224.4 (4.2)24.4 (4.1)
 Educational level5.9
  Primary or secondary44.845.2
 History of asthma or atopy, yes12.744.946.2
 Pet keeping, yes20.833.333.2
 Psychological distress during pregnancy, yes22.17.27.7
 Parity, multiparous2.842.042.2
 Smoked during pregnancy, yes11.322.622.6
 Gestational hypertensive disorders, yes12.34.14.3
 Gestational diabetes, yes3.30.70.7
Infant characteristics
 Sex, female0.050.350.3
 Gestational age (weeks)*0.440.1 (26.7–43.4)40.1 (26.7–43.4)
 Birth weight (g)0.03455 (543)3456 (543)
 Ethnicity, non-European1.528.528.6
 Breastfeeding, never6.57.67.6
 Day care attendance age 1 year, yes28.663.361.0
 Lower respiratory tract infections age 1 year, yes17.013.213.3
 Passive smoking age 1 year, yes17.316.117.6
 Peak height velocity (PHV; cm/year)2.249.3 (8.5)
 Peak weight velocity (PWV; kg/year)0.012.1 (2.1)
 Body mass index at adiposity peak (BMIAP; kg/m2)7.817.6 (0.8)
 Age at adiposity peak (AGEAP; months)7.88.3 (0.7)
Child characteristics
 Age at the time of respiratory outcomes (years)0.09.8 (0.3)
 Allergic sensitisation, yes19.133.033.1
  FVC (L)2.33 (0.4)
  FEV1 (L)2.02 (0.3)
  FEV1/FVC (%)86.7 (5.7)
  FEF75 (L/s)1.14 (0.3)
 Current asthma, yes15.37.8
 Body mass index age 10 years (z-score)0.20.2 (1.0)0.2 (1.0)
  • Values are percentages for categorical variables and means (SD) or medians (range) for continuous variables.

  • Data on early childhood growth patterns (PHV, PWV, BMIAP, AGEAP) and respiratory outcomes (spirometry parameters and current asthma) were not imputed.