Table 1.
Infant and maternal characteristics by gestational age at birth (1973–1979)
| Gestational Age, n (%)
|
|||||
|---|---|---|---|---|---|
| 22–27 weeks (N=165) | 28–34 weeks (N=7,414) | 35–36 weeks (N=17,328) | 37–42 weeks (N=583,248) | ≥43 weeks (N=18,656) | |
| Sex | |||||
| Male | 90 (54.5) | 4,199 (56.6) | 9,680 (55.9) | 298,967 (51.3) | 9,348 (50.1) |
| Female | 75 (45.4) | 3,215 (43.4) | 7,648 (44.1) | 284,281 (48.7) | 9,308 (49.9) |
| Maternal Marital Status | |||||
| Married/cohabiting | 119 (72.1) | 5,075 (68.4) | 12,194 (70.4) | 440,303 (75.5) | 13,436 (72.0) |
| Never married | 23 (13.9) | 983 (13.3) | 2,050 (11.8) | 54,509 (9.4) | 2,107 (11.3) |
| Divorced/widowed | 20 (12.1) | 1,201 (16.2) | 2,807 (16.2) | 81,862 (14.0) | 2,891 (15.5) |
| Unknown | 3 (1.8) | 155 (2.1) | 277 (1.6) | 6,574 (1.1) | 222 (1.2) |
| Maternal Education | |||||
| Compulsory HS or less (≤9 years) | 49 (29.7) | 2,321 (31.3) | 5,295 (30.6) | 154,640 (26.5) | 5,420 (29.0) |
| Practical HS or some theoretical HS (10–11 years) | 76 (46.1) | 3,433 (46.3) | 7,902 (45.6) | 271,371 (46.5) | 8,710 (46.7) |
| Theoretical HS and/or college (≥12 years) | 37 (22.4) | 1,467 (19.8) | 3,782 (21.8) | 148,993 (25.6) | 4,251 (22.8) |
| Unknown | 3 (1.8) | 193 (2.6) | 349 (2.0) | 8,244 (1.4) | 275 (1.5) |
| Family Income | |||||
| Lowest quartile | 51 (30.9) | 2,089 (28.2) | 4,563 (26.3) | 134,100 (23.0) | 4,489 (24.1) |
| Second quartile | 35 (21.2) | 1,833 (24.7) | 4,480 (25.9) | 150,154 (25.7) | 4,717 (25.3) |
| Third quartile | 42 (25.5) | 1,850 (25.0) | 4,310 (24.9) | 149,836 (25.7) | 4,813 (25.8) |
| Highest quartile | 37 (22.4) | 1,642 (22.1) | 3,975 (22.9) | 149,158 (25.6) | 4,637 (24.9) |
Abbreviation: HS = High school.