Table 1.
Characteristics of the study population and the Prevalence Proportion (PP) for major congenital anomalies in relation to the socio-occupational status of the couple in The Danish National Birth Cohort, 1996–2003
| Socio-occupational status |
|||||||||
|---|---|---|---|---|---|---|---|---|---|
| High |
Middle |
Low |
|||||||
| N | Percent | PP | N | Percent | PP | N | Percent | PP | |
| All | 54 011 | 100.0 | 24 104 | 100.0 | 3320 | 100.0 | |||
| Age (years) | |||||||||
| 24 | 1493 | 2.8 | 4.2 | 2875 | 12.1 | 3.5 | 715 | 22.1 | 4.2 |
| 24–29 | 16 508 | 31.1 | 4.3 | 9570 | 40.4 | 4.3 | 1139 | 35.1 | 4.0 |
| >30 | 35 055 | 66.1 | 4.1 | 11 233 | 47.5 | 4.1 | 1387 | 42.8 | 4.6 |
| BMIa | |||||||||
| Underweight (<20) | 3644 | 7.1 | 4.0 | 1407 | 6.1 | 4.1 | 243 | 7.9 | 4.0 |
| Normal weight (21–24) | 29 915 | 58.4 | 4.0 | 10 708 | 46.9 | 4.2 | 1284 | 41.5 | 3.4 |
| Overweight (25–29) | 13 560 | 26.5 | 4.4 | 7162 | 31.4 | 4.2 | 917 | 29.6 | 4.3 |
| Obesity (>30) | 4086 | 8.0 | 4.5 | 3564 | 15.6 | 4.0 | 653 | 21.1 | 5.7 |
| Folic acid | |||||||||
| No intake | 27 252 | 50.6 | 4.4 | 10 165 | 42.3 | 4.4 | 1182 | 35.8 | 4.2 |
| Intake | 26 561 | 49.4 | 3.8 | 13 839 | 57.7 | 3.9 | 2120 | 64.2 | 4.1 |
| Smoking | |||||||||
| Mother | |||||||||
| Non-smoker | 42 619 | 78.9 | 4.0 | 15 563 | 51.9 | 4.0 | 1617 | 48.7 | 4.1 |
| Smoker | 11 392 | 21.1 | 4.5 | 8541 | 28.5 | 4.1 | 1703 | 51.3 | 4.8 |
| Smoker >5 cig/day | 6209 | 11.5 | 3.7 | 5856 | 19.6 | 4.3 | 1334 | 40.2 | 4.3 |
| Father | |||||||||
| Non-smoker | 39 728 | 73.6 | 4.1 | 14 776 | 61.3 | 4.2 | 1774 | 53.4 | 4.5 |
| Smoker | 14 283 | 26.4 | 4.2 | 9328 | 38.7 | 4.0 | 1576 | 46.6 | 4.0 |
| Mother–Father | |||||||||
| Non-smokers | 34 105 | 63.1 | 4.1 | 11 244 | 46.6 | 3.9 | 1074 | 32.3 | 4.1 |
| One of them smokes | 14 134 | 26.2 | 4.3 | 7851 | 32.6 | 4.2 | 1243 | 37.5 | 4.0 |
| Both are smokers | 5769 | 10.7 | 4.1 | 5009 | 20.8 | 4.0 | 1003 | 30.2 | 4.0 |
| Alcohol consumption before pregnancy (gram/week) | |||||||||
| 0 | 27 213 | 50.4 | 4.2 | 15 480 | 64.2 | 4.1 | 2334 | 70.3 | 4.5 |
| 1–20 | 3240 | 6.0 | 4.2 | 1405 | 5.8 | 5.0 | 189 | 5.7 | 3.7 |
| 20–40 | 10 057 | 18.6 | 4.0 | 3388 | 14.1 | 3.8 | 331 | 10.0 | 4.2 |
| >40 | 13 501 | 25.0 | 4.2 | 3831 | 15.9 | 4.2 | 466 | 14.0 | 2.1 |
| Alcohol consumption after pregnancy (gram/week) | |||||||||
| 0 | 28 302 | 70.1 | 4.2 | 14 716 | 79.6 | 4.0 | 2300 | 85.4 | 4.4 |
| 1–20 | 6228 | 15.4 | 4.3 | 2024 | 10.9 | 4.0 | 211 | 7.8 | 5.2 |
| 20–40 | 4782 | 11.9 | 4.4 | 1365 | 7.4 | 5.0 | 139 | 5.2 | 1.4 |
| >40 | 1040 | 2.6 | 3.0 | 393 | 2.1 | 3.5 | 42 | 1.6 | 4.7 |
a: BMI, Pre-pregnancy Body Mass Index (kg/m2)
PP, Prevalence Proportion per 100 births
Percentages may not add up to 100 because of missing responses