Table 2

Sample characteristics, Child Health and Development Study, 1964–67

Final stratified
random sample
(n = 399)
 Cases meeting
study criteria
(n = 1291)
 Cases followed
up at 5 years
(n = 3412)
 CHDS study
population
(n = 20754)
Characteristics*
 N
 %†
 N
 %
 N
 %
 N
 %
Maternal age







     < 20
 28
 7
 68
 5
 230
 7
 1731
 9
     20–29
 242
 61
 786
 61
 2099
 62
 12028
 59
     ≥ 30
 128
 32
 436
 34
 1068
 31
 6724
 33
Parity







     0
 122
 31
 400
 31
 1077
 32
 6289
 31
     1–2
 177
 44
 605
 47
 1572
 47
 9270
 45
     ≥ 3
 100
 25
 286
 22
 717
 21
 5031
 24
Race/ethnicity







     White
 194
 49
 648
 50
 1970
 58
 1347
 66
     African-American
 165
 41
 496
 38
 1041
 31
 4936
 24
     Hispanic
 7
 2
 40
 3
 130
 4
 678
 3
     Asian
 20
 5
 70
 5
 150
 4
 783
 4
     Multi-racial/other
 13
 3
 37
 3
 108
 3
 597
 3
Mother's education







     Not High School graduate
 76
 19
 208
 16
 500
 17
 3341
 19
     High School graduate
 160
 40
 484
 38
 1118
 37
 6661
 38
     Some college
 163
 41
 599
 46
 1378
 46
 7549
 43
Father's education







     Not High School graduate
 74
 19
 211
 20
 496
 17
 2997
 18
     High School graduate
 111
 29
 339
 32
 789
 27
 4607
 28
     Some college
 122
 32
 431
 41
 979
 34
 4329
 26
     College grad/RN
 76
 20
 286
 27
 643
 22
 4681
 28
Sex of infant







     Female
 213
 53.4
 658
 51.0
 1722
 50.5
 9451
 48.8
     Male
 186
 46.6
 633
 49.0
 1690
 49.5
 9927
 51.2

*Data missing for some characteristics for some study participants.

†Percentages may not total 100% due to rounding.

Hertz-Picciotto et al. Environmental Health 2008 7:37   doi:10.1186/1476-069X-7-37