Descriptive characteristics by sex, the Medical Research Council National Survey of Health and Development, 1946–2014
| Males (n=1499) | Females (n=1409) | p Value for sex difference test | |
| Pubertal status at age 14–15 years | |||
| Fully mature | 370 (24.7) | ||
| Advanced stage puberty | 457 (30.5) | ||
| Early-stage puberty | 512 (34.2) | ||
| Prepubescent | 160 (10.7) | ||
| Age at menarche (years) | |||
| ≤11 | 238 (16.9) | ||
| 12 | 402 (28.5) | ||
| 13 | 501 (35.6) | ||
| ≥14 | 268 (19.0) | ||
| Leisure-time physical activity in previous month (yes vs no)* | |||
| Age 36 | 917 (69.1) | 730 (56.9) | p<0.001 |
| Age 43 | 671 (51.1) | 545 (43.6) | p<0.001 |
| Age 53 | 614 (52.2) | 573 (48.6) | p=0.08 |
| Age 60–64 | 294 (34.2) | 335 (37.1) | p=0.2 |
| Age 68 | 369 (39.1) | 401 (40.7) | p=0.5 |
| Birth weight (kg) | p<0.001 | ||
| ≤2.50 (n=129) | 54 (3.6) | 75 (5.3) | |
| 2.51–3.00 (n=475) | 202 (13.5) | 273 (194) | |
| 3.01–3.50 (n=1031) | 497 (33.2) | 534 (37.9) | |
| 3.51–4.00 (n=982) | 547 (36.5) | 435 (30.9) | |
| >4.00 (n=291) | 199 (13.3) | 92 (6.5) | |
| Birth order | p=0.8 | ||
| First born (n=1200) | 624 (41.6) | 576 (40.9) | |
| Second born (n=953) | 482 (32.2) | 471 (33.4) | |
| Third or later born (n=755) | 393 (26.2) | 362 (25.7) | |
| Serious childhood illness | p=0.2 | ||
| No (n=2723) | 1395 (93.1) | 1328 (94.3) | |
| Yes (n=185) | 104 (6.9) | 81 (5.8) | |
| Father’s occupational class age 4 | p=0.9 | ||
| Professional/managerial/technical (n=650) | 341 (n=22.8) | 309 (21.9) | |
| Skilled non-manual (n=547) | 277 (18.5) | 270 (19.2) | |
| Skilled manual (n=902) | 459 (30.6) | 443 (31.4) | |
| Partly skilled or unskilled (n=809) | 422 (28.2) | 387 (27.5) |
*Proportions are for those taking part (at least once per month) in leisure-time physical activity at each age.