Table. Maternal and Child Characteristicsa.
| Characteristic | Gestational Age, No. (%), wk | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 23-24 | 25-26 | 27-28 | 29-30 | 31-32 | 33-34 | 35-36 | 37-38 | 39-41b | Total No. | |
| Sample size, No. | 925 | 2108 | 3365 | 4692 | 8567 | 19 121 | 67 111 | 321 235 | 874 373 | 1 301 497 |
| Maternal characteristics | ||||||||||
| African American | 489 (52.9) | 1059 (50.2) | 1546 (45.9) | 2011 (42.9) | 3564 (41.6) | 7017 (36.7) | 21 431 (31.9) | 85 399 (26.6) | 205 717 (23.5) | 328 233 (25.2) |
| Hispanic | 257 (27.8) | 493 (23.4) | 741 (22.0) | 1107 (23.6) | 1933 (22.6) | 4277 (22.4) | 14 392 (21.4) | 76 179 (23.7) | 209 527 (24.0) | 308 906 (23.7) |
| Foreign born | 275 (29.7) | 535 (25.4) | 730 (21.7) | 1074 (22.9) | 1904 (22.2) | 3978 (20.8) | 13 776 (20.5) | 71 978 (22.4) | 204 757 (23.4) | 299 007 (23.0) |
| Years of education | ||||||||||
| <12 | 211 (22.8) | 583 (27.7) | 985 (29.3) | 1337 (28.5) | 2448 (28.6) | 5372 (28.1) | 17 582 (26.2) | 71 327 (22.2) | 198 464 (22.7) | 298 309 (22.9) |
| 12-15 | 605 (65.4) | 1316 (62.4) | 2008 (59.7) | 2801 (59.7) | 5183 (60.5) | 11 351 (59.4) | 40 183 (59.9) | 196 905 (61.3) | 532 483 (60.9) | 792 835 (60.9) |
| >15 | 109 (11.8) | 209 (9.9) | 372 (11.1) | 554 (11.8) | 936 (10.9) | 2398 (12.5) | 9346 (13.9) | 53 003 (16.5) | 143 426 (16.4) | 210 353 (16.2) |
| Married at birth | 430 (46.5) | 946 (44.9) | 1547 (46.0) | 2272 (48.4) | 4158 (48.5) | 9884 (51.7) | 37 485 (55.9) | 200 399 (62.4) | 547 294 (62.6) | 804 415 (61.8) |
| Age at birth, mean (SD), y | 27.1 (6.6) | 26.7 (6.9) | 26.3 (6.8) | 26.5 (6.8) | 26.3 (6.8) | 26.5 (6.7) | 26.5 (6.5) | 27.0 (6.3) | 26.6 (6.1) | 26.7 (6.2) |
| No. of previous births, mean (SD) | 1.0 (1.4) | 1.0 (1.2) | 1.0 (1.3) | 1.0 (1.3) | 1.0 (1.3) | 1.1 (1.3) | 1.1 (1.3) | 1.1 (1.2) | 1.0 (1.1) | 1.0 (1.2) |
| Infant characteristics | ||||||||||
| Female | 469 (50.7) | 1053 (50.0) | 1701 (50.5) | 2306 (49.1) | 4046 (47.2) | 9026 (47.2) | 32 145 (47.9) | 156 446 (48.7) | 434 287 (49.7) | 641 479 (49.3) |
| Birthweight, mean (SD), g | 845.7 (663.6) | 958.0 (549.1) | 1193.4 (545.4) | 1621.6 (721.7) | 1858.7 (528.9) | 2270.6 (482.4) | 2747.3 (472.5) | 3191.5 (461.4) | 3478.0 (447.7) | 3322.7 (557.6) |
| Congenital anomalies | 18 (1.9) | 41 (1.9) | 69 (2.1) | 100 (2.1) | 142 (1.7) | 285 (1.5) | 922 (1.4) | 2734 (0.9) | 5604 (0.6) | 9915 (0.8) |
a
Data are based on final sample used in the analysis. The P value associated with the F statistic in regression of the maternal/child characteristic on indicators for 8 gestational groups (39-41 weeks omitted as a reference group) was <.001 for all 12 characteristics/regressions.
b
Used as reference group.