Table 1.
Characteristics of children who attended the clinic at age 9 years and their parents (N = 7,121)
| Characteristic | N with data (%) | Mean (SD) or median (IQR) or% | |||
|---|---|---|---|---|---|
| Child | |||||
| Age at DXA scan (months) | 6,851 (96.2) | 118.4 (3.9) | |||
| Sex (%) | Male | 7,121 (100.0) | 49.6 | ||
| Female | 50.4 | ||||
| Height (cm) | 7,047 (99.0) | 139.5 (6.3) | |||
| Weight (kg) | 7,105 (99.8) | 33.2 (29.4–38.4)a | |||
| TBLH BMC (g) | 6,775 (95.1) | 893.8 (184.0) | |||
| TBLH BA (cm2) | 6,775 (95.1) | 1139.5 (164.3) | |||
| TBLH BMD (g/cm2) | 6,775 (95.1) | 0.78 (0.05) | |||
| TBLH ABMC | 6,775 (95.1) | 894.6 (39.8) | |||
| Spine BMC (g) | 5,487 (77.1) | 78.4 (15.7) | |||
| Spine BA (cm2) | 5,487 (77.1) | 100.7 (12.0) | |||
| Spine BMD (g/cm2) | 5,487 (77.1) | 0.77 (0.08) | |||
| Spine ABMC (g) | 5,487 (77.1) | 78.4 (7.1) | |||
| Pubertal stage (%) | Boys | Tanner 1 | 2,365 (67.0) | 82.9 | |
| Tanner 2 | 16.5 | ||||
| Tanner 3+ | 0.6 | ||||
| Girls | Tanner 1 | 2,836 (79.0) | 81.5 | ||
| Tanner 2 | 15.0 | ||||
| Tanner 3+ | 3.5 | ||||
| Age at menarche for girls (years) (%) | Up to 10 | 3,107 (86.5) | 4.7 | ||
| 11+ | 95.3 | ||||
| Gestational age (weeks) | 7,121 (100.0) | 39.5 (1.8) | |||
| Birth weight (kg) | 7,035 (98.8) | 3.4 (0.5) | |||
| Household social class (%) | I | 6,544 (91.9) | 15.5 | ||
| II | 45.1 | ||||
| III NM | 24.8 | ||||
| III M | 10.3 | ||||
| IV/V | 4.3 | ||||
| Mother | |||||
| Age at delivery (years) | 7121 (100.0) | 29.0 (4.6) | |||
| Height (cm) | 6753 (94.8) | 164.1 (6.6) | |||
| Pre-pregnancy BMI (kg/m2) | 6429 (90.3) | 22.2 (20.5–24.4)a | |||
| No. of previous births (%) | 0 | 6879 (96.6) | 45.8 | ||
| 1 | 35.5 | ||||
| 2 | 13.7 | ||||
| 3 | 3.8 | ||||
| 4 or more | 1.2 | ||||
| Smoking during pregnancy (%) | Never | 6379 (89.6) | 78.7 | ||
| 1 or 2 trimesters | 9.5 | ||||
| All trimesters | 11.8 | ||||
| Education (%) | None/CSE | 6860 (96.3) | 13.8 | ||
| Vocational | 8.5 | ||||
| O Levels | 35.2 | ||||
| A Levels | 26.6 | ||||
| Degree | 15.8 | ||||
| Father | |||||
| Age at child’s birth (years) | 5106 (71.7) | 31.4 (5.2) | |||
| Height (cm) | 4931 (69.2) | 176.3 (6.9) | |||
| BMI (kg/m2) | 4887 (68.6) | 24.8 (22.9–26.9)a | |||
| Regular smoker (%) | No | 6679 (93.8) | 65.3 | ||
| Yes | 34.7 | ||||
| Education (%) | None/CSE | 6467 (90.8) | 19.3 | ||
| Vocational | 8.2 | ||||
| O Levels | 21.7 | ||||
| A Levels | 28.5 | ||||
| Degree | 22.2 | ||||
ABMC area-adjusted bone mineral content, BA bone area, BMC bone mineral content, BMD bone mineral density, BMI body mass index, IQR interquartile range, TBLH total body less head
aMedian and interquartile range are shown for skewed variables