Table 1.
The child and family characteristics of the study population (n = 137,530).
| Characteristics | Total | Gender | |
|---|---|---|---|
|
Male
(n = 72,235) |
Female
(n = 65,295) |
||
| Child characteristics | |||
| Children's age (M, SD) | 4.348 (0.68) | 4.356 (0.67) | 4.338 (0.68) |
| BMI (M, SD) | 15.625 (1.63) | 15.783 (1.65) | 15.451 (1.60) |
| Right handedness (n %) | |||
| No | 9,884 (7.19) | 5,763 (7.98) | 4,121 (6.31) |
| Yes | 127,646 (92.81) | 66,472 (92.02) | 61,174 (93.69) |
| Eyesight (n %) | |||
| Normal | 124,053 (90.20) | 65,114 (90.14) | 58,939 (90.27) |
| Abnormal | 13,477 (9.80) | 7,121 (9.86) | 6,356 (9.73) |
| Birth weight (n %) | |||
| <2500g | 587 (4.70) | 297 (4.11) | 290 (4.44) |
| ≥2500g | 136,643 (95.30) | 71,938 (95.89) | 65,005 (95.45) |
| Gestational weeks at birth (n %) | |||
| <34 (very and moderately preterm) | 5,366 (3.90) | 2,905 (4.02) | 2,461 (3.77) |
| 34–36 (late-preterm) | 12,387 (9.01) | 6,809 (9.43) | 5,578 (8.54) |
| 37–38 (early-term) | 35,160 (25.57) | 19,364 (26.81) | 15,796 (24.19) |
| 39–40 (full-term) | 69,529 (50.56) | 35,733 (49.47) | 33,796 (51.76) |
| 41 (late-term) | 8,362 (6.0.8) | 4,045 (5.60) | 4,317 (6.61) |
| >41 (post-term) | 6,726 (4.89) | 3,379 (4.68) | 3,347 (5.13) |
| Delivery mode | |||
| Vaginal delivery | 72,169 (52.48) | 37,018 (51.25) | 35,151 (53.83) |
| Delivery with cesarean section | 65,361 (47.52) | 35,217 (48.75) | 30,144 (46.17) |
| NICU admission | |||
| No | 123,852 (90.05) | 64,548 (89.36) | 59,304 (90.82) |
| Yes | 13,678 (9.95) | 7,687 (10.64) | 5,991 (9.18) |
| Other developmental disordersa | |||
| No | 136,482 (99.24) | 71,606 (99.13) | 65,876 (99.36) |
| Yes | 1,048 (0.76) | 629 (0.87) | 419 (0.64) |
| Family characteristics | |||
| Higher education of motherb (n %) | |||
| No | 63,093 (45.88) | 33,568 (46.47) | 29,525 (45.22) |
| Yes | 74,437 (54.12) | 38,667 (53.53) | 35,770 (54.78) |
| Higher education of father b (n %) | |||
| No | 64,404 (46.83) | 34,177 (47.13) | 30,227 (46.29) |
| Yes | 73,126 (53.17) | 38,058 (52.69) | 35,068 (53.71) |
| Mother's occupation (n %) | |||
| Employed | 85,254 (61.99) | 45,082 (62.41) | 40,172 (55.62) |
| Unemployed | 52,276 (38.01) | 27,153 (37.59) | 25,123 (34.78) |
| Father's occupation (n %) | |||
| Employed | 108,383 (78.81) | 56,998 (78.91) | 51,385 (78.70) |
| Unemployed | 29,147 (21.19) | 15,237 (21.09) | 13,910 (21.30) |
| Family annual per-capita income (RMB)c (n %) | |||
| Below | 26,808 (19.49) | 13,910 (19.26) | 12,898 (19.75) |
| Above or equal to | 110,722 (80.51) | 58,325 (80.74) | 52,397 (80.25) |
| Family structure (n %) | |||
| Single families | 3,404 (2.38) | 1,718 (2.38) | 1,686 (2.58) |
| Nuclear families | 85,510 (62.17) | 45,090 (62.42) | 40,420 (61.91) |
| Extended families | 48,616 (35.35) | 25,427 (35.20) | 23,189 (35.51) |
| The number of children in the family (n %) | |||
| One | 61,431 (44.67) | 31,351 (43.40) | 30,080 (46.07) |
| Two or more | 76,099 (55.33) | 40,884 (56.60) | 35,215 (53.93) |
| Maternal health during pregnancy | |||
| Maternal age at delivery (n %) | |||
| <30 | 41,877 (30.45) | 21,829 (30.22) | 20,048 (30.70) |
| 30–34 | 66,432 (48.30) | 35,049 (48.52) | 31,383 (48.07) |
| ≥35 | 29,221 (21.25) | 15,357 (21.26) | 13,864 (21.23) |
| Smoking or passive smoking during pregnancy (n %) | |||
| No | 99,274 (72.18) | 52,101 (72.13) | 47,173 (72.25) |
| Yes | 38,356 (27.82) | 20,134 (27.87) | 18,122 (27.75) |
| Maternal complications during pregnancyd (n %) | |||
| No | 131,064 (95.30) | 68,910 (95.40) | 62,154 (95.19) |
| Yes | 6,466 (04.70) | 3,325 (4.60) | 3,141 (4.81) |
a
Other developmental disorders included autism spectrum disorder, attention-deficit/hyperactivity disorder, learning disorders.
b
Higher education of mother or father refers to tertiary education leading to the award of an academic degree.
c
The national average family per-capita income of the year before the survey time.
d
Having one of the following maternal complications during pregnancy including gestational diabetes, hypertensive disorders, vaginal bleeding during pregnancy, at risk of miscarriage, use of antibiotics, use of fertility drugs, intrauterine distress, fetal asphyxia.