Table 1 Characteristics of sample (N = 2938)
Variables | n (%) |
|---|---|
Household characteristics | |
 Household income per capita (RMB) (mean, s.d) | 11,482 (28,446) |
 Residential regions | |
  Eastern China | 1172 (39.9) |
  Central China | 852 (29.0) |
  Western China | 914 (31.1) |
 Residence | |
  Urban | 990 (33.7) |
  Rural | 1948 (66.3) |
Parental characteristics | |
 Mother’s educational status | |
  Middle school and below | 2058 (70.1) |
  High school or above | 738 (25.1) |
  Missing data | 142 (4.8) |
 Father’s educational status | |
  Middle school and below | 1951 (66.4) |
  High school or above | 800 (27.2) |
  Missing data | 187 (6.4) |
 ISEI score for mother’s occupation | |
  16–32/unemployment | 2079 (70.8) |
  33–43 | 480 (16.3) |
  44–58 | 256 (8.7) |
  59–90 | 123 (4.2) |
 ISEI score for father’s occupation | |
  16–32/unemployment | 2011 (68.5) |
  33–43 | 564 (19.2) |
  44–58 | 218 (7.4) |
  59–90 | 145 (4.9) |
 Mother’s marital status | |
  Single | 44 (1.5) |
  Married | 2864 (97.5) |
  Divorced/widowed | 22 (0.7) |
  Missing data | 8 (0.3) |
 Parity | |
  Primipara | 1653 (56.3) |
  Multipara | 1285 (43.7) |
 Age of mother (years) (mean, s.d) | 27.35 (4.79) |
 Age of father (years) (mean, s.d) | 29.37 (5.09) |
Infant characteristics | |
 Breastfeeding duration (months) (mean, s.d) | 8.66 (6.15) |
 Gender | |
  Male | 1549 (52.7) |
  Female | 1389 (47.3) |
 Place of delivery | |
  Health facility | 2767 (94.2) |
  Others | 129 (4.4) |
  Missing data | 42 (1.4) |
 Ethnicity | |
  Han | 2590 (88.2) |
  Minority | 348 (11.8) |
 Birth weight | |
  Below 2500 g | 126 (4.3) |
  Normal | 2495 (84.9) |
  Above 4000 g | 245 (8.3) |
  Missing data | 72 (2.5) |
 Gestational age (weeks) | |
  Less than 37 | 1490 (50.7) |
  37–42 | 1343 (45.7) |
  Over 42 | 52 (1.8) |
  Missing data | 53 (1.8) |
 Birth year | |
  2010 | 713 (24.3) |
  2011 | 692 (23.6) |
  2012 | 648 (22.0) |
  2013 | 549 (18.7) |
  2014 | 336 (11.4) |