Table 2.
Basic characteristics of participants in the NSPGDC III–V, 1995–2015.
| 1995 | 2005 | 2015 | P valuea | |
|---|---|---|---|---|
| Gender, n (%) | ||||
| Male | 42,915 (50.2) | 37,560 (50.1) | 44,550 (50.1) | 0.904 |
| Female | 42,539 (49.8) | 37,375 (49.9) | 44,325 (49.9) | |
| Region, n (%) | ||||
| Northern | 28,759 (33.7) | 25,191 (33.6) | 30,108 (33.9) | 0.706 |
| Central | 28,686 (33.6) | 25,248 (33.7) | 29,873 (33.6) | |
| Southern | 28,009 (32.8) | 24,496 (32.7) | 28,894 (32.5) | |
| Father education, n (%) | ||||
| College degree and above | 13,030 (15.2) | 21,113 (28.2) | 46,901 (52.8) | < 0.001 |
| Senior school/ technical secondary school | 26,180 (30.6) | 24,911 (33.2) | 22,850 (25.7) | |
| Junior middle school | 40,587 (47.5) | 26,420 (35.3) | 17,691 (19.9) | |
| Primary school and below | 5594 (6.5) | 2460 (3.3) | 1327 (1.5) | |
| Unknown | 63 (0.1) | 31 (0.0) | 106 (0.1) | |
| Mother education, n (%) | ||||
| College degree and above | 9439 (11.0) | 17,978 (24.0) | 45,758 (51.5) | < 0.001 |
| Senior school/technical secondary school | 25,491 (29.8) | 23,962 (32.0) | 22,627 (25.5) | |
| Junior middle school | 42,704 (50.0) | 29,223 (39.0) | 18,836 (21.2) | |
| Primary school and below | 7751 (9.1) | 3743 (5.0) | 1538 (1.7) | |
| Unknown | 69 (0.1) | 29 (0.0) | 116 (0.1) | |
| Family income, n (%) | ||||
| ≤ ￥30,000 | – | 52,061 (69.5) | 6742 (7.6) | < 0.001 |
| ￥30,000 ~ 49,999 | – | 10,292 (13.7) | 21,505 (24.2) | |
| ￥50,000 ~ 99,999 | – | 6596 (8.8) | 33,036 (37.2) | |
| ￥100,000 ~ 299,999 | – | 1139 (1.5) | 23,504 (26.4) | |
| ≥ ￥300,000 | – | 107 (0.1) | 3682 (4.1) | |
| Unknown | – | 4740 (6.3) | 406 (0.5) | |
| BW(g)b,c | 3300 (401) | 3347 (414) | 3357 (440) | < 0.001 |
| LAZb,d | − 0.06 (1.11) | 0.31 (1.09) | 0.37 (1.03) | < 0.001 |
| WAZb,e | 0.13 (0.93) | 0.37 (0.97) | 0.41 (0.95) | < 0.001 |
| BMIZb,f | 0.24 (0.95) | 0.27 (0.99) | 0.27 (0.98) | < 0.001 |
| HCZb,g | − 0.02 (0.96) | 0.15 (1.01) | 0.02 (0.98) | < 0.001 |
aP values were determined using analysis of variance (ANOVA) test for continuous variables and Chi-square test for categorical variables.
bData are given as means, with standard error (SE) in parentheses.
cBirth weight.
dLength for age Z-score.
eWeight for age Z-score.
fBody mass index for age Z-score.
gHead circumference for age Z-score.