Table 1.
Baseline Characteristics (%) of Children in 5 Cohort Studies After Data Harmonization
| Characteristic | Cohort | ||||
|---|---|---|---|---|---|
|
ALSPAC
a
, 1990–2012 (n = 14,216) |
BCG Study
b
, 1972–1979 (n = 951) |
BiB Study
c
, 2007–2015 (n = 13,445) |
CHS Study
d
, 1936–1964 (n = 1,547) |
PROBIT
e
, 1996–2016 (n = 17,046) |
|
| Age range, yearsf | 0–20 | 0–5 | 0–6 | 9–18 | 0–16 |
| Sex | |||||
| Male | 51 | 54 | 52 | 100 | 52 |
| Female | 49 | 46 | 48 | 0 | 48 |
| Missing data | 0 | 0 | 0 | 0 | 0 |
| Race/ethnicity | |||||
| White European | 79 | 100g | 39 | 100g | 100g |
| South Asian | 0 | 0 | 50 | 0 | 0 |
| Other | 4 | 0 | 8 | 0 | 0 |
| Missing data | 17 | 0 | 3 | 0 | 0 |
| Maternal educational levelh | |||||
| Left school at age 15 or 16 years | 55 | 0 | 43 | 0 | 4 |
| Left school at age 17 or 18 years | 19 | 0 | 12 | 0 | 82 |
| College degree or higher | 11 | 0 | 21 | 0 | 14 |
| Missing data | 15 | 100 | 24 | 100 | 0 |
| Paternal occupationi | |||||
| Class I or II | 22 | 17 | 13 | 55 | 11 |
| Class III | 36 | 58 | 19 | 21 | 60 |
| Class IV, V, or other | 21 | 23 | 44 | 3 | 25 |
| Missing data | 21 | 2 | 24 | 21 | 4 |
| No. of weight measurementsj | 157,000 | 12,737 | 78,110 | 89,070 | 205,864 |
| No. of measurements per childk | 10 (10) | 14 (1) | 5 (3) | 57 (18) | 13 (5) |
| Age at last measurement, yearsk | 13.8 (13.1) | 5 (0) | 4.7 (2.7) | 17.8 (1.5) | 16.0 (1) |
Abbreviations: ALSPAC, Avon Longitudinal Study of Parents and Children; BCG, Barry Caerphilly Growth; Bib, Born in Bradford; CHS, Christ’s Hospital School; PROBIT, Promotion of Breastfeeding Intervention Trial.
a South West England.
b South East Wales.
c Center of North England.
d South East England.
e Republic of Belarus.
f Values are expressed as range.
g These cohorts had no record of race/ethnicity. On the basis of the populations from which they were recruited, we assigned all participants to White European race/ethnicity.
h “Left school at age 15 or 16 years” in the United Kingdom means that the mother's highest academic qualification was either a Certificate of Secondary Education, Ordinary Level, or a General Certificate of Secondary School Education. “Left school at age 17 or 18 years” means the mother's highest academic achievement, generally, was the Advanced Level (A-Level). “College degree or higher” means the mother's highest academic achievement was either an undergraduate academic degree (awarded by colleges and universities upon completion of ≥3 years of study) or a postgraduate qualification (such as a master's-level or doctoral degree).
i Social class I or II: professional or managerial occupation; social class III: intermediate occupation; social class IV or V or other: routine or unskilled occupation, or all other occupations (not categorized above).
j Values are expressed as total number.
k Values are expressed as median (interquartile range).