Table 1.
Participant characteristics (N = 43,159).
| Characteristics | n (%) |
|---|---|
| Fathers’ weekly working hours category | |
| ≥0 to ≤40 h | 9,328 (21.6) |
| >40 to ≤45 h | 5,744 (13.3) |
| >45 to ≤50 h | 10,414 (24.1) |
| >50 to ≤55 h | 4,155 (9.6) |
| >55 to ≤65 h | 6,979 (16.2) |
| >65 h | 6,539 (15.2) |
| Father’s age (years) | |
| ≤24 | 2,644 (6.1) |
| 25–29 | 10,105 (23.4) |
| 30–34 | 14,355 (33.3) |
| ≥35 | 15,963(37.0) |
| Missing | 92 (0.2) |
| Father’s highest educational level | |
| Junior high school or high school | 17,599 (40.8) |
| Technical junior college, technical/vocational college, or associate degree | 10,214 (23.7) |
| Bachelor’s degree, graduate degree (master’s/doctorate) | 14,952 (34.6) |
| Missing | 394 (0.9) |
| Father’s alcohol intake during mother’s pregnancy | |
| Never drank | 9,095 (21.1) |
| Ex-drinker | 1,511 (3.5) |
| Current drinker | 32,425 (75.1) |
| Missing | 128 (0.3) |
| Father’s smoking status at mother’s pregnancy | |
| Never | 12,561 (29.1) |
| Previously did, but quit before learning of mother’s pregnancy | 10,176 (23.6) |
| Previously did, but quit after learning of mother’s pregnancy | 2,053 (4.8) |
| Currently smoking | 17,696 (41.0) |
| Missing | 673 (1.6) |
| Father’s AQ-J-10 score during mother’s pregnancy | |
| 0–6 | 40,182 (93.1) |
| ≥7 | 2,839 (6.6) |
| Missing | 138 (0.3) |
| Annual household income (JPY) | |
| <4 million | 15,375 (35.6) |
| 4 to <6 million | 13,856 (32.1) |
| ≥6 million | 11,270 (26.1) |
| Missing | 2,658 (6.2) |
| Coresident family members of the father–mother pair | |
| Twin or more of the surveyed infant(s), yes | 395 (0.9) |
| Older sibling(s) of the surveyed infant(s), yes | 22,305 (51.7) |
| Mother’s parent(s), yes | 4,096 (9.5) |
| Mother’s parent(s)-in-law, yes | 5,358 (12.4) |
| Year the mother became pregnant | |
| ≤2011 | 15,109 (35.0) |
| 2012 | 14,351 (33.3) |
| ≥2013 | 13,625 (31.6) |
| Missing | 74 (0.2) |
| Mother’s postpartum depression at 1 month after delivery a | |
| Yes | 6,163 (14.3) |
| Missing | 713 (1.7) |
| Infant’s sex | |
| Male | 22,015 (51.0) |
| Female | 21,144 (49.0) |
AQ-J-10, Short form of the Autism-Spectrum Quotient Japanese version; JPY, Japanese Yen. aPostpartum depression: total Edinburgh Postnatal Depression Scale score of ≥9.