Table 1 Sociodemographic characteristics of mothers and infants in different maternal rural-to-urban migrant status
| Â | Maternal rural-to-urban migrant status | p-value | |
|---|---|---|---|
Local (n = 4381) | Migrant (n = 2515) | ||
Maternal age, n (%) a |  |  | <  0.001 |
 < 25 | 577 (13.20) | 433 (17.28) |  |
 25- | 1562 (35.74) | 971 (38.75) |  |
 30- | 1265 (28.94) | 741 (29.57) |  |
 35- | 778 (17.80) | 297 (11.85) |  |
 40–53 | 189 (4.32) | 64 (2.55) |  |
Maternal BMI, n (%) b | Â | Â | 0.033 |
 Underweight (<  18.5 kg/m2) | 579 (13.98) | 351 (15.07) |  |
 Normal weight (18.5–23.9 kg/m2) | 2671 (64.49) | 1544 (66.29) |  |
 Overweight (24.0–27.9 kg/m2) | 651 (15.72) | 326 (14.00) |  |
 Obesity (≥ 28.0 kg/m2) | 241 (5.82) | 108 (4.64) |  |
Infant birthweight, n (%) c | Â | Â | 0.288 |
 < 2500 g | 164 (3.79) | 81 (3.26) |  |
 2500–3999 g | 3775 (87.28) | 2202 (88.54) |  |
 ≥ 4000 g | 386 (8.92) | 204 (8.20) |  |
Infant sex, n (%) | Â | Â | 0.627 |
 Male | 2224 (50.76) | 1292 (49.24) |  |
 Female | 2157 (51.37) | 1223 (48.63) |  |
Maternal education level, n (%) d | Â | Â | 0.607 |
 Primary school and below | 264 (6.03) | 158 (6.29) |  |
 Junior high school | 1071 (24.48) | 638 (25.40) |  |
 Senior high school | 859 (19.63) | 464 (18.47) |  |
 College and above | 2181 (49.85) | 1252 (49.84) |  |
Occupation, n (%) e |  |  | <  0.001 |
 Unemployment | 1562 (35.69) | 937 (37.35) |  |
 Informal employment | 1410 (32.21) | 932 (37.15) |  |
 Formal employment | 1405 (32.10) | 640 (25.51) |  |
Ethnicity, n (%) f |  |  | <  0.001 |
 Han | 3656 (83.57) | 1996 (79.59) |  |
 Others | 719 (16.43) | 512 (20.41) |  |
Place of residence, n (%) |  |  | <  0.001 |
 Metropolis | 1910 (43.60) | 1639 (65.17) |  |
 Medium sized/small cities | 2471 (56.40) | 876 (34.83) |  |
Delivery method, n (%) g |  |  | <  0.001 |
 Vaginal | 2618 (59.92) | 1615 (64.29) |  |
 Caesarean section | 1751 (40.08) | 897 (35.71) |  |
Preterm birth, n (%) h | Â | Â | 0.140 |
 No | 4095 (95.19) | 2377 (95.96) |  |
 Yes | 207 (4.81) | 100 (4.04) |  |