Table 2 Characteristics of the study population, Kaiser Permanente Northern California births, 1995–1999
From: Prenatal exposure to β2-adrenergic receptor agonists and risk of autism spectrum disorders
Characteristics | No. (%) | P valuea | |
|---|---|---|---|
ASD cases (n = 291) | Controls (n = 284) | ||
Gender (male) | 243 (83.51) | 230 (80.99) | 0.43 |
Plurality | |||
Singleton | 273 (93.81) | 273 (96.13) | 0.21 |
Twin or triplet | 18 (6.19) | 11 (3.87) | |
Birth order | |||
First born | 121 (41.58) | 122 (42.96) | 0.18 |
Second born | 113 (38.83) | 92 (32.39) | |
Third or later born | 57 (19.59) | 70 (24.65) | |
Maternal age | |||
<20 | 3 (1.03) | 8 (2.82) | 0.14 |
20–24 | 25 (8.59) | 29 (10.21) | |
25–29 | 64 (21.99) | 79 (27.82) | |
30–34 | 104 (35.74) | 99 (34.86) | |
35–39 | 84 (28.87) | 60 (21.13) | |
≥40 | 11 (3.78) | 9 (3.17) | |
Maternal education | |||
<HS | 10 (3.44) | 18 (6.34) | <0.001 |
HS | 49 (16.84) | 78 (27.46) | |
College | 163 (56.01) | 152 (53.52) | |
Post-graduate | 68 (23.37) | 34 (11.97) | |
Unknown | 1 (0.34) | 2 (0.70) | |
Maternal race/ethnicity | |||
White, non-Hispanic | 157 (53.95) | 138 (48.59) | 0.23 |
White, Hispanic | 40 (13.75) | 60 (21.13) | |
Black | 27 (9.28) | 24 (8.45) | |
Asian | 28 (9.62) | 24 (8.45) | |
Other | 39 (13.4) | 38 (13.38) | |
Gestational age | |||
<37 Weeks | 25 (8.59) | 17 (5.99) | 0.23 |
≥37 Weeks | 266 (91.41) | 267 (94.01) | |
Birthweight | |||
<2,500 g | 24 (8.25) | 10 (3.52) | 0.02 |
≥2,500 g | 267 (91.75) | 274 (96.48) | |
Parity | |||
No previous births | 126 (43.3) | 118 (41.55) | 0.03 |
One previous birth | 114 (39.18) | 91 (32.04) | |
Two or more previous births | 51 (17.53) | 75 (26.41) | |
Birth year | |||
1995 | 85 (29.21) | 75 (26.41) | 0.81 |
1996 | 65 (22.34) | 72 (25.35) | |
1997 | 59 (20.27) | 57 (20.07) | |
1998 | 59 (20.27) | 62 (21.83) | |
1999 | 23 (7.90) | 18 (6.34) | |