Table 2.
Demographic characteristics after propensity score matching
| Variables | MLBW (n = 50,060) | No MLBW (n = 50,060) | p value |
|---|---|---|---|
| Gender | >0 .999a | ||
| Female | 30,115 (60.16) | 30,115 (60.16) | |
| Male | 19,945 (39.84) | 19,945 (39.84) | |
| Agec | >0 .999b | ||
| Mean ± SD | 3.26 + 2.31 | 3.26 + 2.31 | |
| Economic status | > 0.999a | ||
| Low income | 3543 (7.08) | 3543 (7.08) | |
| Confounders | |||
| Blindness and low vision | 3 (0.01) | 3 (0.01) | >0 .999a |
| Epilepsy | 180 (0.36) | 180 (0.36) | >0 .999a |
| Fetal and neonatal hemorrhage | 12 (0.02) | 12 (0.02) | >0 .999a |
| Communicating hydrocephalus | 4 (0.01) | 4 (0.01) | >0 .999a |
| Intrauterine hypoxia and birth asphyxia | 15 (0.03) | 15 (0.03) | >0 .999a |
| Other perinatal jaundice | 37 (0.07) | 37 (0.07) | >0 .999a |
| Microcephalus | 12 (0.02) | 12 (0.02) | > 0.999a |
| Patent ductus arteriosus | 363 (0.73) | 363 (0.73) | >0 .999a |
| Pneumonia | 1592 (3.18) | 1592 (3.18) | > 0.999a |
| Pneumothorax | 3 (0.01) | 3 (0.01) | > 0.999a |
| Other respiratory conditions of fetus and newborn | 217 (0.43) | 217 (0.43) | > 0.999a |
MLBW: marginally low birthweight, defined as term-born infants with birth weight between 2000 and 2499 g. No MLBW: term-born infants with birth weight ≥ 2500 g
aChi-squared test; b t-test
cAge was calculated using 2013/12/31 as the time point to minus the date of birth