Table 1.
Characteristics of mothers included in the study and all mothers at Chiba regional center of JECS
| Respondent mothers included in the analysis | All mothers participating in JECS in Chiba | |
|---|---|---|
| N (%) | N (%) | |
| Number | 1762 | 5176 |
| Age at delivery in years | ||
| <29 | 579 (32.9) | 1930 (37.3) |
| 30–34 | 629 (35.7) | 1801 (34.8) |
| ≥35 | 554 (31.4) | 1444 (27.9) |
| Missing | 0 | 1 (0.02) |
| Educational background | ||
| Junior high | 52 (3.0) | 220 (4.3) |
| Senior high | 494 (28.0) | 1608 (31.1) |
| Junior college or vocational | 777 (44.1) | 2050 (39.6) |
| Undergraduate or above | 439 (24.9) | 1001 (19.3) |
| Missing | 0 | 297 (5.7) |
| Annual household income during pregnancy (million Japanese Yen) | ||
| <4 | 531 (30.1) | 1674 (32.3) |
| 4 to <6 | 610 (34.6) | 1640 (31.7) |
| ≥6 | 571 (32.4) | 1399 (27.0) |
| Missing | 50 (2.8) | 463 (8.9) |
| History of chronic disease or disability in the family | ||
| No | 1247 (70.8) | NA |
| Yes | 515 (29.2) | |
NA not applicable