Polychlorinated Biphenyl and Organochlorine Pesticide Concentrations in Maternal Mid-Pregnancy Serum Samples: Association with Autism Spectrum Disorder and Intellectual Disability

http://dx.doi.org/10.1289/EHP277



Table 2. Basic characteristics of the study population by case status.
Characteristic ASD
(n = 545)
ID
(= 181)
GP
(= 418)
Abbreviations: ASD, autism spectrum disorder; GP, general population controls; ID, intellectual disability (without ASD).
*t-Test comparing ASD to GP controls significant (p < 0.05).
**Chi-squared test comparing the categorical variable across all three diagnostic groups significant (p < 0.05). Missing categories were not included in chi-squared tests.
Maternal age (mean ± SD) 29.9 ± 5.6* 27.2 ± 6.3 28.7 ± 5.4
Paternal age (mean ± SD) 35.7 ± 14.6 36.9 ± 21.2 34.0 ± 14.2
Child year of birth (mean ± SD) 2001 ± 1.0 2001 ± 1.0 2001 ± 1.0
No. of prenatal visits (mean ± SD) 15.1 ± 13.9 15.4 ± 16.0 13.8 ± 10.1
No. of total live births (mean ± SD) 1.8 ± 0.9* 2.3 ± 1.5 2.1 ± 1.0
Child birth weight in grams (mean ± SD) 3390.9 ± 608.7 3,009 ± 868 3385.0 ± 588.8
Child gestational age in days (mean ± SD) 274.3 ± 27.1* 268.2 ± 30.2 279.0 ± 36.1
Multiparous [n (%)] 298 (55)** 119 (66) 259 (62)
Maternal birth place [n (%)] **
United States 272 (50) 79 (44) 202 (48)
Mexico 131 (24) 84 (46) 128 (31)
Other 142 (26) 18 (10) 88 (21)
Maternal race/ethnicity [n (%)] **
Non-Hispanic white 192 (35) 32 (18) 138 (33)
Asian 82 (15) 9 (5) 45 (11)
Black, Pacific Islander, other 48 (9) 13 (7) 35 (8)
Hispanic 218 (40) 126 (70) 197 (47)
Missing 5 (1) 1 (0.6) 3 (0.7)
Maternal education [n (%)] **
Less than high school 97 (18) 76 (42) 102 (24)
High school 118 (22) 50 (28) 113 (27)
Some college/college degree 222 (41) 42 (23) 143 (34)
Postgraduate 100 (18) 11 (6) 56 (13)
Missing 8 (1.5) 2 (1) 4 (1)
Maternal age ≥ 35 years [n (%)] 103 (19)** 22 (12) 52 (13)
Paternal age ≥ 35 years [n (%)] 229 (42)** 63 (35) 142 (34)
Prenatal care initiated ≥ 3 months gestation [n (%)] 101 (19) 47 (27) 81 (19)
Insurance status at delivery [n (%)] **
Self and other 19 (3) 7 (4) 18 (4)
Private insurance 289 (53) 49 (27) 207 (49)
Government program 237 (44) 125 (69) 193 (46)
Child sex **
Male 446 (82) 104 (57) 345 (83)
Female 99 (18) 77 (43) 73 (17)
Child preterm (< 37 weeks) [n (%)] 66 (13)** 37 (22) 44 (11)
Child low birth weight (< 2,500 g) [n (%)] 42 (8)** 40 (22) 21 (5)