Table 1.
Sociodemographic characteristics of study participants before imputation of missing variables [n (%) or mean (std)], New York City Longitudinal Study of Early Development Birth Years 1994–1998
| Overall (n = 187,401) | Term Birth (≥37 weeks) (n = 171,828) | Preterm birth (<37 weeks) (n = 15,573) | |
|---|---|---|---|
|
| |||
| Maternal age at birth (years) | 27.3 (6.42) | 27.3 (6.38) | 27.7 (6.82) |
| Total live deliveries including current pregnancy | |||
| Maternal education (years) | 11.8 (2.6) | 11.9 (2.7) | 11.7 (2.5) |
| Neighborhood deprivation index | 0.0 (1.0) | 0.0 (1.0) | 0.2 (1.0) |
| Perchloroethylene (μg/m3) | 0.8 (0.4) | 0.8 (0.4) | 0.8(0.4) |
| Diesel particulate matter (μg/m3) | 9.5 (8.7) | 9.5 (8.7) | 9.5 (8.2) |
| Math z-score | 0.0 (1.0) | 0.1 (1.0) | −0.2 (1.0) |
| Language z-score | 0.0 (1.0) | 0.0 (1.0) | −0.2 (1.0) |
| Highest venous blood lead level test (μg/dL) | 4.7 (3.5) | 4.7 (3.5) | 4.8 (3.6) |
| Borough of residence (%) | |||
| Manhattan | 27174 (14.5) | 24730 (14.4) | 2444 (15.7) |
| Bronx | 37913 (20.2) | 34523 (20.1) | 3390 (21.8) |
| Brooklyn | 67310 (35.9) | 61597 (35.8) | 5713 (36.7) |
| Queens | 44947 (24.0) | 41657 (24.2) | 3290 (21.1) |
| Staten Island | 10057 (5.4) | 9321 (5.4) | 736 (4.7) |
| Maternal occupation (%) | |||
| Works at home only | 90578 (48.3) | 82996 (48.3) | 7582 (48.7) |
| Student | 16389 (8.7) | 14982 (8.7) | 1407 (9.0) |
| Not employed | 18392 (9.8) | 16697 (9.7) | 1695 (10.9) |
| Other occupation | 57592 (30.7) | 53048 (30.9) | 4544 (29.2) |
| Missing | 4450 (2.4) | 4105 (2.4) | 345 (2.2) |
| Maternal marital status—Unmarried | 78563 (41.9) | 73344 (42.7) | 5219 (33.5) |
| Nativity & race | |||
| Foreign-born Black non-Hispanic | 22523 (12.0) | 20491 (11.9) | 2032 (13.0) |
| Foreign-born White non-Hispanic | 10051 (5.4) | 9522 (5.5) | 529 (3.4) |
| Foreign-born Hispanic | 39328 (21.0) | 36818 (21.4) | 2510 (16.1) |
| US-born Black Hispanic | 40282 (21.5) | 35667 (20.8) | 4615 (29.6) |
| US-born White Hispanic | 21796 (11.6) | 20414 (11.9) | 1382 ( 8.9) |
| US-born Hispanic | 32276 (17.2) | 29140 (17.0) | 3136 (20.1) |
| Asian and Other (US- or foreign-born) | 21145 (11.3) | 19776 (11.5) | 1369 (8.8) |
| Season of birth | |||
| Winter | 46199 (24.7) | 42255 (24.6) | 3944 (25.3) |
| Spring | 46594 (24.9) | 42757 (24.9) | 3837 (24.6) |
| Summer | 47918 (25.6) | 43920 (25.6) | 3998 (25.7) |
| Fall | 46690 (24.9) | 42896 (25.0) | 3794 (24.4) |
| Any complication during delivery—Yes (%) | 65137 (34.8) | 57634 (33.5) | 7503 (48.2) |
| Alcohol use during pregnancy | 1071 (0.6) | 791 (0.5) | 280 (1.8) |
| Yes (%) | |||
| Reported tobacco use during pregnancy | 10727 (5.7) | 9163 (5.3) | 1564 (10.0) |
| Yes (%) | |||
| Quartiles of Diesel PM | |||
| 1st quartile (<6.35μg/m3) | 46988 (25.1) | 43412 (25.3) | 3576 (23.0) |
| 2nd quartile (6.35–7.67 μg/m3) | 46939 (25.0) | 42717 (24.9) | 4222 (27.1) |
| 3rd quartile (7.67–9.74 μg/m3) | 46702 (24.9) | 42853 (24.9) | 3849 (24.7) |
| 4th quartile (9.74–140 μg/m3) | 46772 (25.0) | 42846 (24.9) | 3926 (25.2) |
| Quartiles of perchloroethylene (%) | |||
| 1st quartile (<0.58 μg/m3) | 46869 (25.0) | 43345 (25.2) | 3524 (22.6) |
| 2nd quartile (0.58–0.68 μg/m3) | 46974 (25.1) | 42764 (24.9) | 4210 (27.0) |
| 3rd quartile (0.68–0.84 μg/m3) | 46740 (24.9) | 42972 (25.0) | 3768 (24.2) |
| 4th quartile (0.84–9.20 μg/m3) | 46818 (25.0) | 42747 (24.9) | 4071 (26.1) |