Table 1.
Study population characteristics, by SDI levels.
| Study Population | High-SEP tracts (SDI Q1) | Mid-range SEP tracts (SDI Q2 + Q3) | Low-SEP tracts (SDI Q4) | |
|---|---|---|---|---|
|
| ||||
| n = 243,853 | n = 60,963 | n = 121,809 | n = 61,081 | |
|
| ||||
| Term birth weight (g) | % (n) | % (n) | % (n) | % (n) |
|
| ||||
| < 1,500 | 0.04 (88) | 0.04 (26) | 0.03 (32) | 0.05 (30) |
| 1,500 – 2,499 | 2.6 (6,402) | 2.2 (1,361) | 2.7 (3,291) | 2.9 (1,750) |
| 2500 – 3,999 | 90.3 (220,156) | 90.2 (54,978) | 90.3 (110,017) | 90.3 (55,161) |
| ≥ 4,000 | 7.1 (17,207) | 7.5 (4,598) | 7.0 (8,469) | 6.8 (4,140) |
|
| ||||
| Maternal SEP | % (n) | % (n) | % (n) | % (n) |
|
| ||||
| Education | ||||
| < 9 yrs. | 8.1 (19,731) | 2.1 (1,300) | 8.8 (10,700) | 12.7 (7,731) |
| 9 – 11 yrs. | 17.6 (42,819) | 4.3 (2,622) | 17.8 (21,719) | 30.3 (18,487) |
| 12 yrs. (High school) | 23.9 (58,286) | 10.3 (6,266) | 28.4 (35,544) | 28.7 (17,476) |
| 13 – 15 yrs. | 21.9 (53,376) | 16.8 (10,249) | 24.9 (30,293) | 21.0 (12,825) |
| 16 yrs. (BA) | 16.3 (39,793) | 33.2 (20,213) | 13.2 (16,129) | 5.7 (3,451) |
| > 16 yrs. | 12.2 (29,857) | 33.3 (20,213) | 6.9 (8,424) | 1.8 (1,120) |
|
| ||||
| Medicaid status | ||||
| Yes | 61.1 (149,106) | 23.8 (14,485) | 68.6 (83,582) | 83.6 (51,039) |
| No | 38.9 (94,747) | 86.2 (46,478) | 31.4 (38,227) | 16.4 (10.042) |
|
| ||||
| Ethnicity | ||||
| US-born White | 19.4 (47,233) | 44.3 (27,021) | 14.6 (17,725) | 4.1 (2,496) |
| Foreign-born White | 9.4 (22,912) | 20.3 (12,387) | 8.0 (9,763) | 1.3 (762) |
| US-born Black | 12.0 (29,339) | 2.8 (1,732) | 13.8 (16,779) | 17.7 (10,828) |
| Foreign-born Black | 9.8 (23,856) | 2.1 (1,295) | 13.4 (16,299) | 10.3 (6,262) |
| US-born Hispanic | 12.4 (30,346) | 6.5 (3,974) | 11.3 (13,794) | 20.6 (12,578) |
| Foreign-born Hispanic | 21.8 (53,248) | 7.4 (4,529) | 21.5 (26,161) | 36.9 (22,558) |
| US-born Asian | 1.2 (2,899) | 2.9 (1,783) | 0.8 (981) | 0.2 (135) |
| Foreign-born Asian | 14.0 (34,020) | 13.5 (8,251) | 16.7 (20,307) | 8.9 (5,462) |
|
| ||||
| Adjustment covariates | % (n) | % (n) | % (n) | % (n) |
|
| ||||
| Maternal age (years) | ||||
| < 20 | 6.6 (16,108) | 1.7 (1,024) | 6.6 (8,056) | 11.5 (7.028) |
| 20 – < 25 | 20.8 (50,608) | 8.1 (4,964) | 23.4 (28,504) | 28.1 (17,140) |
| 25 – < 30 | 26.6 (64,814) | 20.0 (12,178) | 28.9 (35,145) | 28.6 (17,491) |
| 30 – < 35 | 26.4 (64,481) | 37.8 (23,062) | 24.3 (29,556) | 19.4 (11,863) |
| 35 – < 40 | 15.3 (37,246) | 25.1 (15,324) | 13.2 (16,025) | 9.7 (5,897) |
| ≥ 40 | 4.4 (10,596) | 7.2 (4,411) | 3.7 (4,523) | 2.7 (1,662) |
|
| ||||
| Pre-pregnancy BMI | ||||
| < 18.5 (Underweight) | 5.5 (13,445) | 6.4 (4,108) | 5.3 (6,456) | 4.7 (2,881) |
| 18.5 – < 25 (Normal) | 54.3 (132,442) | 68.7 (41,851) | 51.6 (62,810) | 45.5 (27,781) |
| 25 – < 30 (Overweight) | 23.7 (57,842) | 16.3 (9,929) | 25.5 (31,082) | 27.6 (16,831) |
| ≥ 30 (Obese) | 16.5 (40,124) | 8.3 (5,075) | 17.6 (21,461) | 22.3 (13,588) |
|
| ||||
| Prenatal care received | ||||
| Yes | 99.5 (242,570) | 99.6 (60,746) | 99.5 (121,156) | 99.3 (60,668) |
| No | 0.5 (1,283) | 0.4 (217) | 0.5 (653) | 0.7 (413) |
|
| ||||
| Previous live births | ||||
| 0 | 46.6 (113,644) | 56.3 (34,314) | 44.0 (53,582) | 42.2 (25,748) |
| 1 | 29.5 (71,990) | 29.3 (17,884) | 29.9 (36,356) | 29.1 (17,741) |
| 2 | 13.5 (33,011) | 9.4 (5,727) | 14.3 (17,433) | 16.1 (9,851) |
| ≥ 3 | 10.3 (25,208) | 5.0 (3,038) | 11.9 (14,429) | 12.7 (7,741) |
|
| ||||
| Gestational age (weeks) | ||||
| 37 | 8.1 (19,654) | 7.0 (4,284) | 8.6 (10,147) | 8.6 (5,223) |
| 38 | 18.5 (44,994) | 17.6 (10,727) | 18.7 (22,876) | 18.7 (11,391) |
| 39 | 34.5 (84,237) | 35.0 (21,319) | 34.7 (41,742) | 34.7 (21,176) |
| 40 | 29.6 (72,284) | 31.7 (19,288) | 28.7 (35,454) | 28.7 (17,542) |
| 41 | 8.6 (21,002) | 8.2 (4,975) | 8.8 (10,569) | 8.8 (5,368) |
| 42 | 0.7 (1,682) | 0.6 (370) | 0.8 (931) | 0.6 (381) |
|
| ||||
| Conception season | ||||
| Dec – Feb | 28.8 (70,242) | 28.4 (17,305) | 29.0 (35,326) | 28.8 (17,611) |
| Mar – May | 20.4 (49,686) | 20.0 (12,200) | 20.4 (24,839) | 20.7 (12,647) |
| Jun – Aug | 22.0 (53,670) | 22.4 (13,654) | 22.0 (26,787) | 21.7 (13,229) |
| Sep – Nov | 28.8 (70,255) | 29.2 (17,804) | 28.6 (34,857) | 28.8 (17,594) |
|
| ||||
| Conception year | ||||
| 2007 | 16.7 (40,812) | 16.8 (10,212) | 16.7 (20,292) | 16.9 (10,308) |
| 2008 | 38.7 (94,238) | 38.7 (23,562) | 38.6 (47,042) | 38.7 (23,634) |
| 2009 | 37.2 (90,615) | 37.2 (22,709) | 37.2 (45,301) | 37.0 (22,605) |
| 2010 | 7.5 (18,188) | 7.4 (4,480) | 7.5 (9,174) | 7.4 (4,534) |
|
| ||||
| Full-gestation air pollution exposure estimate | Mean (SD) | Mean (SD) | Mean (SD) | Mean (SD) |
| NO2 near-residence mean concentration (ppb) | 26.8 (5.3) | 28.1 (8.0) | 25.7 (3.9) | 27.8 (3.6) |
| PM2.5 near-residence mean concentration (μg/m3) | 11.8 (1.9) | 12.3 (2.4) | 11.3 (1.5) | 12.2 (1.7) |