Table 2.
Results of subgroup analysis
| Factors | Groups | Low birth weight | Preterm delivery | ||||||
|---|---|---|---|---|---|---|---|---|---|
| No. of studies | OR (95 % CI) | P | I2 (%) | No. of studies | OR (95 % CI) | P | I 2 | ||
| Design type | Prospective | 27 | 1.93(1.64, 2.28) | <0.001 | 75.8 | 23 | 1.60(1.39, 1.84) | <0.001 | 59.8 |
| Retrospective | 16 | 2.05(1.72, 2.45) | <0.001 | 62.2 | 17 | 1.67(1.49, 1.86) | <0.001 | 39.5 | |
| Study period | Before 1995 | 15 | 1.90(1.61, 2.25) | <0.001 | 54.4 | 15 | 1.59(1.31, 1.93) | <0.001 | 41.2 |
| 1995–2004 | 14 | 1.72(1.42, 2.08) | <0.001 | 63.1 | 15 | 1.55(1.34, 1.80) | <0.001 | 66.1 | |
| 2005–2015 | 14 | 2.52(1.90, 3.33) | <0.001 | 83.7 | 10 | 1.79(1.55, 2.06) | <0.001 | 37.9 | |
| Study location | Africa | 24 | 2.18(1.84, 2.59) | <0.001 | 73.5 | 19 | 1.56(1.40, 1.75) | <0.001 | 52.6 |
| America | 11 | 1.80(1.49, 2.19) | <0.001 | 73.1 | 11 | 1.69(1.53, 1.88) | <0.001 | 6.2 | |
| Europe | 2 | 1.34(0.90, 2.00)a, | 0.15 | 0 | 5 | 1.40(0.73, 2.68)a | 0.32 | 80.4 | |
| Asia | 6 | 1.99(1.05, 3.74) | 0.03 | 77.3 | 5 | 1.60(1.10, 2.35) | 0.02 | 27.3 | |
| Country economic | Developing | 31 | 2.12(1.81, 2.48) | <0.001 | 72.5 | 26 | 1.60(1.44, 1.76) | <0.001 | 48.9 |
| Developed | 12 | 1.75(1.44, 2.12) | <0.001 | 71.9 | 14 | 1.67(1.41, 1.98) | <0.001 | 52.5 | |
| ARVs exposure | No | 10 | 1.75(1.42, 2.17) | <0.001 | 51.7 | 9 | 1.54(1.23, 1.92) | <0.001 | 44.5 |
| Not stated | 17 | 2.07(1.78, 2.42) | <0.001 | 51.2 | 17 | 1.55(1.32, 1.82) | <0.001 | 56.2 | |
| Yes | 16 | 2.04(1.61, 2.57) | <0.001 | 82.1 | 14 | 1.77(1.55, 2.02) | <0.001 | 52.4 | |
| Overall | 43 | 1.98(1.76, 2.23) | <0.001 | 71.7 | 40 | 1.62(1.49, 1.77) | <0.001 | 51.8 | |
No number, CI confidence interval, ARVs antiretroviral drugs, OR odds ratio
aNo significant difference/no statistical significance (P > 0.05)