Association between risk factors and the parallel classes of soiling and constipation (n≤8435 depending on risk factor)
| n (%) | Constipation alone | Soiling alone | Constipation with soiling | Omnibus P value | |
| OR (95% CI) | OR (95% CI) | OR (95% CI) | |||
| Sex | |||||
| Female (ref) | 4082 (52%) | <0.001 | |||
| Male | 4353 (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 | |||
| Sometimes | 4312 (54%) | 2.08 (1.56 to 2.77) | 1.12 (0.82 to 1.52) | 1.22 (0.84 to 1.78) | |
| Usually hard | 2235 (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 months | 3579 (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 months | 2677 (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 skilled | 6579 (85%) | 0.736 | |||
| Partly skilled/unskilled | 1178 (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 level | 2916 (35%) | 0.92 (0.76 to 1.12) | 0.82 (0.62 to 1.08) | 1.16 (0.87 to 1.54) | |
| Vocational or none | 1909 (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 rented | 312 (4.1%) | 0.73 (0.44 to 1.20) | 1.12 (0.62 to 2.02) | 1.26 (0.69 to 2.29) | |
| Subsidised rented | 832 (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 | |||
| No | 581 (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 weeks | 435 (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 g | 372 (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 development | 7931 | 0.95 (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 months | 168 (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 months | 1056 (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 months | 2650 (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).