Multivariate logistic regression predicting the likelihood of survey non-response of each questionnaire
| Variable | Resumed group | Discontinued group | Continued group |
| AICc=4081.9 | AICc=8210.7 | AICc=22 715.5 | |
| OR (95% CI) | OR (95% CI) | OR (95% CI) | |
| Age at delivery | |||
| <25 | Reference | Reference | Reference |
| 25–29 | 1.00 (0.81 to 1.25) | 0.85 (0.73 to 0.99) | 0.55 (0.49 to 0.61) |
| 30–34 | 0.98 (0.77 to 1.24) | 0.71 (0.60 to 0.84) | 0.40 (0.35 to 0.45) |
| ≥35 | 1.27 (0.97 to 1.66) | 0.83 (0.73 to 0.95) | 0.40 (0.35 to 0.46) |
| Smoking habits after delivery | |||
| Never smoked | Reference | Reference | Reference |
| Ex-smoker who quit before pregnancy | 1.00 (0.82 to 1.22) | 1.09 (0.95 to 1.25) | 1.16 (1.05 to 1.29) |
| Ex-smoker who quit after pregnancy | 1.45 (1.17 to 1.79) | 1.13 (0.99 to 1.30) | 1.94 (1.75 to 2.15) |
| Smoker | 1.23 (0.94 to 1.61) | 1.52 (1.26 to 1.85) | 3.24 (2.83 to 3.72) |
| Alcohol consumption after delivery | |||
| Never drank | Reference | Reference | Reference |
| Ex-drinker who quit before pregnancy | 1.05 (0.74 to 1.49) | 0.88 (0.71 to 1.10) | 1.07 (0.91 to 1.27) |
| Drinker | 0.87 (0.65 to 1.16) | 1.19 (0.96 to 1.47) | 1.33 (1.14 to 1.54) |
| Educational status (≥13 years/<13 years) | 0.88 (0.74 to 1.04) | 0.90 (0.80 to 1.01) | 0.74 (0.68 to 0.81) |
| Family income per year | |||
| <4 million yen | Reference | Reference | Reference |
| 4–12 million yen | 1.12 (0.95 to 1.33) | 0.92 (0.82 to 1.02) | 0.91 (0.84 to 0.99) |
| ≥12 million yen | 1.22 (0.69 to 2.14) | 1.50 (1.00 to 2.24) | 1.37 (1.22 to 1.45) |
| Health status after delivery | |||
| Poor | Reference | Reference | Reference |
| Fair | 1.27 (0.87 to 1.85) | 0.80 (0.60 to 1.06) | 0.79 (0.65 to 0.96) |
| Good | 1.12 (0.77 to 1.63) | 0.75 (0.57 to 1.00) | 0.73 (0.60 to 0.88) |
| Very good | 1.09 (0.75 to 1.58) | 0.69 (0.52 to 0.92) | 0.66 (0.54 to 0.80) |
| K6 during pregnancy (≥13/<13) | 1.00 (0.71 to 1.42) | 1.32 (1.03 to 1.70) | 1.33 (1.12 to 1.58) |
| EPDS after delivery (≥9/<9) | 1.14 (0.91 to 1.42) | 1.01 (0.87 to 1.17) | 1.10 (0.90 to 1.23) |
| Physical anomalies in neonates (yes/no) | 0.86 (0.54 to 1.36) | 1.34 (0.95 to 1.89) | 1.24 (0.98 to 1.57) |
| Siblings living with the child after delivery | |||
| 0 | Reference | Reference | Reference |
| 1 | 1.13 (0.95 to 1.36) | 1.10 (0.98 to 1.25) | 1.47 (0.35 to 1.61) |
| ≥2 | 1.28 (1.04 to 1.57) | 1.35 (1.17 to 1.55) | 2.10 (1.90 to 2.32) |
| Primary caregiver (mother/others) | 1.52 (0.72 to 3.20) | 1.61 (0.98 to 2.64) | 2.05 (1.46 to 2.88) |
| Partner participation* | |||
| Non-participation | Reference | Reference | Reference |
| Inactive participation | 1.41 (0.84 to 2.35) | 1.82 (1.26 to 2.62) | 3.75 (2.92 to 4.82) |
| Active participation | 1.10 (0.94 to 1.29) | 0.88 (0.79 to 0.98) | 0.65 (0.60 to 0.71) |
*If the partner agreed to participate but did not return the questionnaire, his participation was classified as inactive participation. If the partner returned the questionnaire, his participation was classified as active participation. Partners who did not agree to participate or could not be contacted to request participation were classified under ‘non-participation’.
AIC, Akaike's information criterion; EPDS, Edinburgh Postnatal Depression Scale; K6, Kessler Psychological Distress Scale.