Table 2. Summary of influencing factors.
| Inclusion of literature | Country | Type of study | Sample capacity | Influencing factors | NOS score | |
|---|---|---|---|---|---|---|
| Cases | Controls | |||||
| Gao et al. (2022) | China | Case control study | 125 | 122 | ①②③ | 7 |
| Li et al. (2013) | China | Case control study | 181 | 106 | ④⑤⑥⑦ | 7 |
| Zhou et al. (2010) | China | Case control study | 190 | 134 | ①③⑯⑰ | 7 |
| Dong (2021) | China | Case control study | 60 | 40 | ③④⑤⑥ | 7 |
| Yu et al. (2020) | China | Cohort study | 1,100 | 147 | ①③④⑤⑥⑧⑨⑩⑫ | 9 |
| de Almeida et al. (2014) | Brazil | Cohort study | 593 | 754 | ⑦⑨⑩ | 9 |
| Akter, Parvin & Yasmeen (2013) | Bangladesh | Cohort study | 785 | 1,525 | ①③⑤⑬⑭ | 9 |
| Miller, Lee & Gould (2011) | USA | Cohort study | 4,932 | 3,850 | ①②③④⑤⑥⑦⑨⑪⑮ | 9 |
| Wilson et al. (2018) | Sweden | Cohort study | 3,132 | 2,729 | ⑦ | 9 |
| Lee et al. (2019) | Korea | Cohort study | 3,462 | 1,211 | ①③⑤⑥⑧⑨⑩⑫ | 9 |
Note:
① Birth weight; ② Multiple births; ③ Neonatal resuscitation; ④ Antenatal steroids; ⑤ Cesarean section; ⑥ Apgar score; ⑦ Failure to keep warm in time; ⑧ Small for gestational age (SGA); ⑨ Maternal combined complications; ⑩ Gestational age; ⑪ Race; ⑫ Premature rupture of membranes (PROM); ⑬ Newborn age (hour); ⑭ Socioeconomic status; ⑮ Spontaneous delivery; ⑯ Not born in our hospital; ⑰ Born in the cold season.