Table 1.
Characteristics of women at different periods of their lives, by their reported birth weight
| Birth weight |
χ2 value for heterogeneitya (all P values <0.001 unless specified) | |||||
|---|---|---|---|---|---|---|
| <2.5 kg (N = 61 308) | 2.5–2.9 kg (N = 86 377) | 3.0–3.4 kg (N = 157 437) | 3.5–3.9 kg (N = 85 256) | ≥4.0 kg (N = 62 645) | ||
| Year of birth, mean (SD) | 1942 | 1942 | 1942 | 1943 | 1942 | 0.8 (P = 0.4) |
| Age at baseline (years), mean (SD) | 59.1 (4.6) | 58.9 (4.5) | 58.7 (4.5) | 58.6 (4.5) | 59.3 (4.7) | 0.0 (P = 0.9) |
| Birth and family | ||||||
| Maternal height (cm), mean (SD) | 159.5 (7.1) | 159.7 (6.9) | 160.5 (6.8) | 160.9 (6.8) | 161.3 (7.0) | 2982 |
| Paternal height (cm), mean (SD) | 173.7 (8.1) | 173.8 (7.7) | 174.4 (7.5) | 174.9 (7.5) | 175.2 (7.7) | 1579 |
| Mother smoked during pregnancy (%) | 34.3 | 31.3 | 30.0 | 28.6 | 27.8 | 659 |
| Was breast fed as an infant (%) | 56.1 | 68.9 | 73.3 | 75.4 | 75.4 | 5749 |
| Mother alive when birth details were collected (%) | 26.5 | 33.8 | 35.4 | 35.8 | 28.8 | 157 |
| Adolescence, early adulthood, and reproductive factors | ||||||
| Age at menarche (years), mean (SD) | 12.8 (1.7) | 12.9 (1.6) | 12.9 (1.5) | 12.9 (1.6) | 12.9 (1.6) | 7.1 (P = 0.008) |
| Adult height (cm), mean (SD) | 160.2 (6.7) | 161.2 (6.5) | 162.6 (6.4) | 163.6 (6.5) | 164.5 (6.6) | 18 590 |
| Nulliparity (%) | 12.7 | 12.3 | 10.1 | 12.1 | 12.3 | 10.2 (P = 0.001) |
| Age the woman was when she had her first baby, mean (SD) | 23.9 (4.3) | 24.1 (4.3) | 24.1 (4.3) | 24.2 (4.3) | 23.9 (4.3) | 0.6 (P = 0.4) |
| Middle age | ||||||
| Lowest fifth of socio-economic status (%) | 21.5 | 18.7 | 17.9 | 18.0 | 20.3 | 47 |
| Ever used hormone therapy for menopause (%) | 55.2 | 55.6 | 56.0 | 55.5 | 54.8 | 0.7 (P = 0.4) |
| Body mass index (kg/m2), mean (SD) | 26.5 (4.9) | 26.0 (4.6) | 26.0 (4.5) | 26.2 (4.7) | 26.7 (4.9) | 180 |
| Current smoker (%) | 12.7 | 11.4 | 11.5 | 11.7 | 13.2 | 8.2 (P = 0.004) |
| Strenuous exercise <1 time per week (%) | 58.7 | 56.6 | 55.0 | 55.4 | 57.9 | 30 |
| Alcohol consumption (g/day), mean (SD) | 5.7 (8.0) | 6.5 (8.5) | 7.0 (8.7) | 7.1 (8.9) | 6.7 (8.8) | 429 |
aχ2 tests of regression models using self-reported birth weight as independent variable.