Table 2 Characteristics of mothers with singleton births, by maternal age
1982 | 1993 | 2004 | |||||||
|---|---|---|---|---|---|---|---|---|---|
Variables | < 16 | 16-19 | 20-29 | < 16 | 16-19 | 20-29 | < 16 | 16-19 | 20-29 |
% | % | % | % | % | % | % | % | % | |
Family income (minimum wage) | |||||||||
≤ 1.0 | 46.9 | 36.0 | 20.7 | 27.8 | 23.5 | 19.5 | 36.8 | 30.8 | 20.5 |
1.1 -3.0 | 50.0 | 52.5 | 48.1 | 48.2 | 48.4 | 43.3 | 50.9 | 50.4 | 47.1 |
3.1 - 6.0 | 3.1 | 8.4 | 19.7 | 17.6 | 21.1 | 23.6 | 10.5 | 15.3 | 23.5 |
> 6.0 | 0.0 | 3.1 | 11.5 | 6.5 | 7.0 | 13.7 | 1.8 | 3.5 | 8.8 |
Total (N) | 64 | 844 | 3,409 | 108 | 810 | 2,779 | 114 | 688 | 2,081 |
P-value | < 0.001a | < 0.001a | < 0.001a | ||||||
< 0.001 b | < 0.001 b | < 0.001 b | |||||||
Schooling (years) | |||||||||
0 | 6.2 | 4.6 | 3.6 | 5.6 | 2.1 | 2.4 | 0.0 | 0.3 | 0.9 |
1 - 4 | 47.7 | 35.2 | 25.5 | 31.5 | 27.9 | 26.0 | 16.7 | 12.3 | 12.9 |
5 - 8 | 41.5 | 50.8 | 42.9 | 61.1 | 58.4 | 45.8 | 75.4 | 61.1 | 36.9 |
9 + | 4.6 | 9.4 | 28.0 | 1.9 | 11.6 | 25.8 | 7.9 | 26.3 | 49.3 |
Total (N) | 65 | 852 | 3,419 | 108 | 810 | 2,776 | 114 | 689 | 2,072 |
P-value | < 0.001a | < 0.001a | < 0.001a | ||||||
< 0.001 b | < 0.001 b | < 0.001 b | |||||||
Skin color | |||||||||
White | 78.5 | 80.1 | 82.7 | 77.8 | 72.6 | 77.6 | 70.2 | 72.7 | 72.9 |
Black and Mixed-race | 21.5 | 20.0 | 17.3 | 22.2 | 27.4 | 22.4 | 29.8 | 27.3 | 27.1 |
Total (N) | 65 | 852 | 3,422 | 108 | 810 | 2,778 | 114 | 689 | 2,084 |
P-value | 0.144 a | 0.012 a | 0.812 a | ||||||
Pre-pregnancy BMI (kg/m 2 )* | |||||||||
< 18.5 | 15.4 | 14.1 | 8.0 | 18.3 | 14.0 | 8.9 | 19.6 | 10.2 | 4.4 |
18.5 - 24.9 | 78.9 | 77.4 | 74.0 | 75.0 | 72.7 | 70.7 | 69.1 | 71.0 | 64.7 |
25.0 - 29.9 | 5.8 | 7.8 | 15.1 | 4.8 | 12.0 | 16.2 | 10.3 | 14.6 | 20.9 |
≥ 30.0 | 0.0 | 0.7 | 2.9 | 1.9 | 1.4 | 4.2 | 1.0 | 4.3 | 10.0 |
Total (N) | 52 | 696 | 2,920 | 104 | 786 | 2,698 | 97 | 630 | 1,918 |
P-value | < 0.001a | < 0.001a | < 0.001a | ||||||
< 0.001 b | < 0.001 b | < 0.001 b | |||||||
Parity | |||||||||
0 | 92.3 | 78.9 | 40.0 | 96.2 | 72.1 | 34.5 | 95.6 | 75.8 | 38.8 |
1 | 7.7 | 18.4 | 33.1 | 3.8 | 22.8 | 32.7 | 2.6 | 18.9 | 29.5 |
2 or more | 0.0 | 2.7 | 26.9 | 0.0 | 5.1 | 32.8 | 1.8 | 5.4 | 31.6 |
Total (N) | 65 | 852 | 3,423 | 106 | 804 | 2,754 | 114 | 689 | 2,083 |
P-value | < 0.001a | < 0.001a | < 0.001a | ||||||
< 0.001b | < 0.001 b | < 0.001 b | |||||||
Marital status | |||||||||
Single | 29.2 | 18.1 | 7.4 | 43.5 | 29.3 | 9.7 | 45.6 | 28.7 | 15.0 |
Married | 70.8 | 81.9 | 92.6 | 56.5 | 70.7 | 90.3 | 54.4 | 71.3 | 85.0 |
Total (N) | 65 | 852 | 3,421 | 108 | 810 | 2,779 | 114 | 689 | 2,084 |
P-value | < 0.001a | < 0.001a | < 0.001a | ||||||