Table 3

Association between risk factors and the parallel classes of soiling and constipation (n≤8435 depending on risk factor)

n (%)Constipation aloneSoiling aloneConstipation with soilingOmnibus P value
OR (95% CI)OR (95% CI)OR (95% CI)
Sex
 Female (ref)4082 (52%)<0.001
 Male4353 (48%)0.63 (0.53 to 0.75)1.78 (1.39 to 2.27)1.38 (1.06 to 1.79)
Hard stools regularity at 2½ years
 Never hard (ref)1414 (18%)<0.001
 Sometimes4312 (54%)2.08 (1.56 to 2.77)1.12 (0.82 to 1.52)1.22 (0.84 to 1.78)
 Usually hard2235 (28%)1.90 (1.40 to 2.60)0.68 (0.46 to 0.99)1.26 (0.85 to 1.89)
Breast feeding
 Child never breast fed (ref)1695 (21%)0.309
 Child breast fed for <6 months3579 (45%)1.25 (0.99 to 1.58)1.34 (0.96 to 1.86)1.08 (0.77 to 1.52)
 Child breastfed for at least 6 months2677 (34%)1.24 (0.97 to 1.59)1.22 (0.86 to 1.73)0.94 (0.65 to 1.35)
Parental social class
 Professional, managerial or skilled6579 (85%)0.736
 Partly skilled/unskilled1178 (15%)0.95 (0.74 to 1.20)1.16 (0.85 to 1.60)0.98 (0.67 to 1.42)
Maternal educational attainment
 A level/degree (ref)3399 (41%)0.358
 O level2916 (35%)0.92 (0.76 to 1.12)0.82 (0.62 to 1.08)1.16 (0.87 to 1.54)
 Vocational or none1909 (23%)0.82 (0.66 to 1.03)0.94 (0.70 to 1.26)0.92 (0.65 to 1.30)
Material hardship at 33 months*
 No material hardship (score<5) (ref.)5733 (73%)0.026
 Material hardship (score≥5)2084 (27%)1.00 (0.82 to 1.22)1.06 (0.81 to 1.40)1.52 (1.15 to 2.00)
Home ownership at 33 months
 Home owned/
 mortgaged (ref.)
6524 (85%)0.401
 Privately rented312 (4.1%)0.73 (0.44 to 1.20)1.12 (0.62 to 2.02)1.26 (0.69 to 2.29)
 Subsidised rented832 (11%)0.74 (0.55 to 1.00)1.01 (0.68 to 1.48)0.92 (0.60 to 1.43)
Car access at 33 months
 Yes (ref.)7230 (93%)0.018
 No581 (7%)0.82 (0.57 to 1.18)1.53 (1.02 to 2.27)1.49 (0.97 to 2.29)
Gestational age at delivery
 ≥37 weeks (ref)8000 (95%)0.334
 <37 weeks435 (5%)0.76 (0.50 to 1.16)1.28 (0.80 to 2.05)1.12 (0.66 to 1.93)
Birth weight
 ≥2500 g (ref)7964 (96%)0.488
 <2500 g372 (4%)1.29 (0.88 to 1.88)1.32 (0.79 to 2.21)1.05 (0.56 to 1.97)
Developmental level at 18 m
 Per 1 SD reduction in development79310.95 (0.87 to 1.05)1.44 (1.28 to 1.62)1.31 (1.13 to 1.51)<0.001
Age at initiation of toilet training
 Unadjusted model<0.001
 Before 6 months168 (2%)1.20 (0.67 to 2.15)1.50 (0.69 to 3.28)1.73 (0.78 to 3.81)
 Between 6 and 15 months1056 (14%)1.22 (0.95 to 1.56)1.09 (0.74 to 1.59)0.81 (0.49 to 1.32)
 Between 15 and 24 months (ref)3841 (50%)
 After 24 months2650 (34%)0.91 (0.75 to 1.12)1.47 (1.13 to 1.91)1.56 (1.17 to 2.07)
  • *Material hardship was assessed using the set of questions: ‘How difficult at the moment do you find it to afford these items? Food, clothing, heating, rent, items for child’: each on a four-point scale from very difficult through to not difficult. Responses were summed and a binary variable was derived to indicate the top 20% of the sample.

  • †Developmental level was assessed using a questionnaire developed by Avon Longitudinal Study of Parents and Children including items from the Denver Developmental Screening Test24 and comprising four domains of development (fine motor, gross motor, communication and social skills). We used a total development score derived from the sum of the scores on each domain. Scores on each domain were adjusted for age in weeks and standardised (using a linear regression model and extracting the residuals) and reversed where appropriate so that high values on all scores reflected a lower level of development (increase in the odds of membership to the latent classes per 1 SD increase in developmental level score).