Table 1. Descriptive statistics of studies contributing to analysis.
EFSOCH and ALSPAC sample size is the number of mother-child pairs in the analysis. NFBC1966 and NFBC1986 sample size is the number of offspring in the analysis.
| Study | ALSPAC | EFSOCH | NFBC1966 | NFBC1986 |
|---|---|---|---|---|
| Country of origin | UK | UK | Finland | Finland |
| Year(s) of birth | 1991–1993 | 2000–2004 | 1966 | 1985–6 |
| Sample size (Male /Female (offspring sex)) | 4570 (2263/3207) | 612 (320/292) | 3691 (1839/1852) | 3078 (1488/1590) |
| Data collection | Identified from obstetric data, records from the ALSPAC measurements, and birth notification | Measured within 12 hours of birth | Measured in hospitals | Measured in hospitals |
| Mean (SD) birth weight (grams) Males | 3553 (491) | 3585 (463) | 3607 (506) | 3626 (543) |
| Mean (SD) birth weight (grams) Females | 3423 (450) | 3447 (475) | 3480 (466) | 3519 (521) |
| Mean (SD) birth weight (grams) | 3490 (476) | 3519 (474) | 3541 (489) | 3572 (535) |
| Mean Maternal age (SD) | 28.0 (4.96) | 30.4 (5.28) | 27.9 (6.5) | 28.0 (5.3) |
| Mean Maternal Prepregnancy BMI (SD) | 22.9 (3.83) | 24.0 (4.45) | 23.16 (3.18) | 22.33 (3.38) |
| Median (IQR) GA (weeks) at delivery | 40 (40–41) | 40 (39–41) | 40 (39–41) | 40 (39–40) |
| Prevalence SGA | 7.48% (b) | 5.88% (b) | 9.90% (c) | 5.80% (c) |
| Prevalence LGA | 10.01% (b) | 11.60% (b) | 11.80% (c) | 15.50% (c) |
| TDI | Not available | 0.25 (3.27) | Not available | Not available |
| Standard Occupational Class (a) | I 5.9% II 31.5% III (non-manual) 42.8% III (manual) 7.8% IV 9.9% V 2.1% |
Not available | I 12.00% II 21.70% III 40.12% IV 9.78% Farmer I 15.04% Farmer II 1.35% |
Professional/entrepreneur 18.8% Skilled, non-manual 17.6% Skilled, manual 41.0% Unskilled/apprentice 4.8% Farmer 7.9% Student/at home 4.0% Sick pension/unemployed 5.9% |
| % First Births | 44.90% | 49.3% | 30.81% | 34.0% |
| Smokers | 24.60% | 13.0% | 19.08% | 18.5% |
| Mean Maternal Height cm (SD) | 164.0 (6.7) | 165.0 (6.3) | 160.0 (5.3) | 163.0 (5.4) |
| Study description paper (PMID) | 22507742; 22507743 | 16466435 | 19060910 | 31321419 |
(a) Derived from Office of Population Censuses & Surveys Standard Occupational Classification (Office of Population Censuses and Surveys (1991) Standard Occupational Classification. Her Majesty's Stationery Office)
(b) SGA and LGA defined using UK 1990 growth standards [23].
(c) SGA and LGA defined using the Swedish 1991 standards [24].