Table 2 Baseline characteristics by gestational age, birth weight, and birth weight z-score adjusted for sex and gestational age in Hong Kong’s “Children of 1997” Birth Cohort.
From: Birth weight and prematurity with lung function at ~17.5 years: “Children of 1997” birth cohort
Characteristics | Gestational age (week) | Birth weight (kg) | Birth weight z-score adjusted for sex and gestational age | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
No. | % | mean | SD | P | mean | SD | P | mean | SD | P | |
Sex | |||||||||||
Female | 1488 | 49.0 | 39.1 | 1.53 | <0.001 | 3.16 | 0.42 | <0.001 | −0.01 | 0.99 | 0.796 |
Male | 1546 | 51.0 | 38.9 | 1.67 | 3.23 | 0.45 | 0.00 | 0.97 | |||
Birth order | |||||||||||
1 | 1403 | 47.5 | 39.1 | 1.60 | 0.012 | 3.16 | 0.42 | <0.001 | −0.12 | 0.96 | <0.001 |
2 | 1225 | 41.5 | 38.9 | 1.62 | 3.21 | 0.45 | 0.07 | 0.98 | |||
3 or above | 323 | 11.0 | 39.0 | 1.50 | 3.29 | 0.43 | 0.27 | 0.98 | |||
Maternal age at birth, years | |||||||||||
≤24 | 294 | 9.7 | 39.3 | 1.69 | <0.001 | 3.17 | 0.40 | 0.399 | −0.16 | 0.88 | 0.004 |
25–29 | 944 | 31.2 | 39.1 | 1.60 | 3.21 | 0.42 | −0.01 | 0.97 | |||
30–34 | 1176 | 38.9 | 39.0 | 1.54 | 3.19 | 0.44 | −0.01 | 0.97 | |||
≥35 | 607 | 20.0 | 38.6 | 1.67 | 3.18 | 0.47 | 0.08 | 1.05 | |||
Maternal smoking | |||||||||||
Smoker | 112 | 3.8 | 39.1 | 1.81 | 0.385 | 3.16 | 0.41 | 0.422 | −0.10 | 0.96 | 0.234 |
Non-smoker | 2839 | 96.2 | 39.0 | 1.60 | 3.20 | 0.44 | 0.00 | 0.98 | |||
Maternal birthplace | |||||||||||
Hong Kong | 1769 | 58.7 | 38.8 | 1.59 | <0.001 | 3.16 | 0.44 | <0.001 | −0.06 | 0.99 | <0.001 |
Mainland China and elsewhere | 1247 | 41.3 | 39.2 | 1.61 | 3.25 | 0.43 | 0.07 | 0.97 | |||
Household income (Quantile) | |||||||||||
1 | 496 | 18.2 | 39.2 | 1.64 | <0.001 | 3.23 | 0.42 | 0.093 | 0.03 | 0.97 | 0.469 |
2 | 552 | 20.3 | 38.9 | 1.71 | 3.20 | 0.47 | 0.03 | 1.03 | |||
3 | 545 | 20.0 | 39.0 | 1.54 | 3.20 | 0.42 | −0.01 | 0.96 | |||
4 | 552 | 20.3 | 38.9 | 1.52 | 3.17 | 0.43 | −0.06 | 1.01 | |||
5 | 575 | 21.1 | 38.8 | 1.57 | 3.17 | 0.43 | −0.04 | 0.94 | |||
Highest parental education at recruitment | |||||||||||
Grade 9 or below | 861 | 28.5 | 39.1 | 1.72 | <0.001 | 3.23 | 0.44 | 0.062 | 0.05 | 0.98 | 0.082 |
Grade 10–11 | 1296 | 42.9 | 39.0 | 1.59 | 3.19 | 0.44 | −0.04 | 1.00 | |||
Grade 12 or above | 863 | 28.6 | 38.8 | 1.50 | 3.18 | 0.43 | −0.00 | 0.96 | |||
Highest parental occupation | |||||||||||
I (professional) | 711 | 26.8 | 38.9 | 1.55 | <0.001 | 3.18 | 0.45 | 0.037 | −0.05 | 0.94 | 0.012 |
II (managerial) | 392 | 14.8 | 38.7 | 1.64 | 3.20 | 0.45 | 0.08 | 0.99 | |||
IIINM (non-manual skilled) | 762 | 28.8 | 39.0 | 1.58 | 3.17 | 0.43 | −0.09 | 1.00 | |||
IIIM (manual skilled) | 444 | 16.8 | 39.2 | 1.62 | 3.24 | 0.43 | 0.06 | 1.04 | |||
VI (semiskilled) | 256 | 9.7 | 39.0 | 1.91 | 3.21 | 0.46 | 0.03 | 1.04 | |||
V (unskilled) | 85 | 3.2 | 39.2 | 1.60 | 3.28 | 0.44 | 0.18 | 1.04 | |||
