Frequency of preterm (<32 weeks’ gestational age) and very preterm (<32 weeks’ gestational age) birth among all livebirths surviving beyond 1 year and among cerebral palsy (CP) cases at age 8 years, by surveillance year, by race and ethnicity, sex, co-occurring epilepsy, and co-occurring autism spectrum disorder (ASD).
| Surveillance year 2006 (birth year 1998) | Surveillance year 2008 (birth year 2000) | Surveillance year 2010 (birth year 2002) | Test for trend P-value | |
|---|---|---|---|---|
| Total number of births surviving to age 1 year | 125 166 | 130 884 | 128 722 | |
| Number with gestational age information at birth | 125 025 | 130 803 | 128 676 | |
| % Preterm (95% CI) | 11.9 (11.7, 12.0) | 11.9 (11.7, 12.0) | 12.5 (12.3, 12.6) | <0.001 |
| % Very preterm (95% CI) | 1.8 (1.7, 1.9) | 1.8 (1.8, 1.9) | 1.8 (1.2, 1.4) | 0.381 |
| Total number of white, non-Hispanic births surviving to age 1 year (% of total white non-Hispanic births) | 75 141 | 74 437 | 70 688 | |
| % Preterm (95% CI) | 9.9 (9.7, 10.1) | 10.3 (10.0, 10.5) | 10.8 (10.6, 11.1) | <0.001 |
| % Very preterm (95% CI) | 1.2 (1.1, 1.3) | 1.3 (1.2, 1.3) | 1.3 (1.2, 1.4) | 0.161 |
| Total number of black, non-Hispanic births surviving to age 1 year (% of total black non-Hispanic births) | 37 587 | 38 898 | 37 005 | |
| % Preterm (95% CI) | 16.6 (16.2, 16.9) | 16.1 (15.7, 16.5) | 17.1 (16.7, 17.5) | 0.057 |
| % Very preterm (95% CI) | 3.3 (3.1, 3.5) | 3.2 (3.1, 3.4) | 3.1 (2.9, 3.2) | 0.075 |
| Total number of Hispanic births surviving to age 1 year (% of total Hispanic births) | 6156 | 9348 | 11 831 | |
| % Preterm (95% CI) | 8.5 (7.8, 9.2) | 9.1 (8.5, 9.7) | 9.4 (8.9, 10.0) | 0.038 |
| % Very preterm (95% CI) | 1.0 (0.8, 1.3) | 0.9 (0.7, 1.1) | 1.1 (0.9, 1.3) | 0.367 |
| CP cases with no documented postneonatal aetiology (age 8 years) with available birth certificate data | ||||
| Total number of CP cases | 291 | 294 | 267 | |
| Number with gestational age information at birth | 290 | 294 | 267 | |
| % Preterm (95% CI) | 52.1 (46.2, 57.9) | 52.0 (46.2, 57.9) | 48.7 (42.6, 54.9) | 0.213 |
| % Very preterm (95% CI) | 35.9 (30.3, 41.7) | 35.4(30.0, 41.2) | 31.1 (25.7, 37.1) | 0.241 |
| Number of white non-Hispanic cases | 161 | 147 | 118 | |
| % Preterm (95% CI) | 44.7 (37.0, 52.7) | 45.6 (37.4, 54.0) | 43.2 (34.2, 52.7) | 0.825 |
| % Very preterm (95% CI) | 22.2 (17.9, 31.7) | 27.9 (21.0, 36.0) | 23.7 (16.6, 32.6) | 0.989 |
| Number of black non-Hispanic cases | 103 | 111 | 110 | |
| % Preterm (95% CI) | 61.2 (51.0, 70.5) | 58.6 (48.8, 67.7) | 55.5 (45.7, 64.8) | 0.398 |
| % Very preterm (95% CI) | 54.2 (42.4, 62.3) | 44.1 (34.8, 53.9) | 39.1 (30.1, 48.9) | 0.052 |
| Number of Hispanic CP cases | 13 | 25 | 25 | |
| % Preterm (95% CI) | 76.9 (46.0, 93.8) | 52.0 (31.8, 71.7) | 44.0 (25.0, 64.7) | 0.068a |
| % Very preterm (95% CI) | 53.9 (26.1, 79.6) | 28.0 (12.9, 49.6) | 24.0 (10.2, 45.5) | |
| Number of boys | 158 | 181 | 143 | |
| % Preterm (95% CI) | 50.6 (42.6, 58.6) | 54.7 (47.2, 62.1) | 49.0 (40.1, 57.4) | 0.795 |
| % Very preterm (95% CI) | 34.2 (27.0, 42.2) | 35.4 (28.4, 42.9) | 33.6 (26.0, 42.0) | 0.919 |
| Number of girls | 132 | 113 | 124 | |
| % Preterm (95% CI) | 53.8 (44.9, 62.4) | 47.8 (38.4, 57.4) | 48.4 (39.4, 57.5) | 0.383 |
| % Very preterm (95% CI) | 37.9 (29.7, 46.8) | 35.4 (26.8, 45.0) | 28.2 (20.7, 37.1) | 0.105 |
| Number with co-occurring epilepsy | 99 | 122 | 114 | |
| % Preterm (95% CI) | 43.4 (33.6, 53.8) | 46.7 (37.7, 55.9) | 46.5 (37.2, 56.0) | 0.665 |
| % Very preterm (95% CI) | 29.3 (20.8, 39.4) | 24.6 (17.5, 33.4) | 28.1 (20.3, 37.4) | 0.869 |
| Number with no co-occurring epilepsy | 191 | 172 | 153 | |
| % Preterm (95% CI) | 56.5 (49.2, 63.6) | 55.8 (48.1, 63.3) | 50.3 (42.8, 59.1) | 0.263 |
| % Very preterm (95% CI) | 39.3 (32.4, 46.6) | 43.0 (35.6, 50.8) | 33.3 (26.1, 41.5) | 0.303 |
| Number with co-occurring ASD | 20 | 20 | 23 | |
| % Preterm (95% CI) | 55.0 (32.1, 76.2) | 50.0 (27.9, 72.2) | 52.2 (31.2, 72.6) | 0.862 |
| % Very preterm (95% CI) | 30.0 (12.8, 54.3) | 30.0 (12.8, 54.3) | 34.8 (17.2, 57.2) | 0.733 |
| Number with no co-occurring ASD | 270 | 274 | 244 | |
| % Preterm (95% CI) | 51.9 (45.7, 57.9) | 52.2 (46.1, 58.2) | 48.4 (42.0, 54.8) | 0.439 |
| % Very preterm (95% CI) | 36.3 (30.6, 42.4) | 35.8 (30.2, 41.8) | 30.7 (25.1, 37.0) | 0.192 |
ASD, autism spectrum disorder; CI, confidence interval; CP, cerebral palsy.
a
P-value not calculated due to small expected cell sizes.