Table 1.
Characteristics of mothers of children included in analysis. Values are numbers (percentages) unless stated otherwise
| Characteristic | Gestational age of babies at birth (weeks) | P values comparing gestational age groups* | ||||
|---|---|---|---|---|---|---|
| <32 (n=225) | 32-33 (n=192) | 34-36 (n=1107) | 37-38 (n=3655) | 39-41 (n=12 540) | ||
| Mean (SD) age at time of child’s birth (years) | 28.5 (6.2) | 29.9 (6.0) | 28.9 (6.2) | 29.2 (5.9) | 28.7 (5.8) | 0.006 |
| Single mother | 44 (17.2) | 25 (8.8) | 212 (16.0) | 617 (13.9) | 2082 (14.0) | 0.04 |
| Socioeconomic status: | 0.87 | |||||
| Managerial and professional | 57 (26.1) | 43 (26.6) | 282 (29.1) | 943 (29.6) | 3358 (30.6) | |
| Long term unemployed | 21 (7.0) | 24 (9.4) | 124 (8.9) | 407 (8.4) | 1420 (8.1) | |
| Education: | 0.001 | |||||
| Degree | 61 (28.8) | 52 (31.2) | 310 (9.7) | 1017 (30.8) | 3756 (33.8) | |
| No qualifications | 52 (20.9) | 28 (11.7) | 189 (14.5) | 626 (13.5) | 1932 (11.9) | |
| Moderate/heavy alcohol use during pregnancy† | 14 (7.3) | 16 (8.4) | 71 (7.8) | 236 (6.6) | 880 (7.3) | 0.03 |
| Smoked during pregnancy | 63 (27.7) | 45 (19.1) | 307 (25.4) | 851 (22.2) | 2773 (20.4) | 0.007 |
| Duration of breastfeeding: | <0.001 | |||||
| Never | 71 (28.9) | 58 (29.8) | 445 (36.8) | 1333 (33.0) | 4195 (29.4) | |
| ≥4 months | 38 (17.4) | 35 (21.3) | 229 (22.9) | 944 (28.4) | 3870 (34.5) | |
Means and percentages are weighted with sampling and non-response weights
*χ2 tests for categorical variables and F tests for continuous variables; calculated for weighted, clustered data.
†≥3 units/week or ≥3 units/occasion.