TABLE 2.
Results of meta-analysis for all outcomes.
| Outcome | Included studies | Number of studies | Number of patients | MD/RR/OR | 95% CI | P | I 2 (%) | Model |
|---|---|---|---|---|---|---|---|---|
| /Peto’s OR | ||||||||
| Primary outcomes | ||||||||
| Miscarriage | all RCTs | 5 | 1,313 | 0.85 | 0.69-1.05 | 0.14 | 1 | Fix |
| RCTs with low to moderate risk of bias | 2 | 585 | 0.91 | 0.71-1.17 | 0.47 | 12 | Fix | |
| all cohort study | 5 | 397 | 0.12 a | 0.07-0.19 | <0.001 | 62 | Fix | |
| Cohort study with low to moderate risk of bias | 1 | 19 | 1.5 | 0.12-18.36 | 0.75 | 0 | Fix | |
| Preterm birth | all RCTs | 5 | 1,282 | 0.80 | 0.59-1.08 | 0.14 | 0 | Fix |
| RCTs with low to moderate risk of bias | 1 | 540 | 0.85 | 0.53-1.36 | 0.49 | 0 | Fix | |
| all Cohort study | 2 | 134 | 0.95 a | 0.24-3.79 | 0.94 | 0 | Fix | |
| Preeclampsia | all RCTs | 1 | 115 | 0.68 | 0.12-3.91 | 0.66 | 0 | Fix |
| Secondary outcomes | ||||||||
| Placenta abruption | all RCTs | 1 | 115 | 0.14 a | 0.00-6.94 | 0.32 | 0 | Fix |
| all cohort study | 1 | 96 | 7.09 a | 0.14-357.80 | 0.33 | 0 | Fix | |
| Birth weight | all RCTs | 1 | 375 | −36.00 | -170.41-98.41 | 0.60 | 0 | Fix |
| Gestational age at delivery | all RCTs | 1 | 374 | −0.10 | -0.61-0.41 | 0.70 | 0 | Fix |
| Neonatal admission | all RCTs | 1 | 42 | 1.33 | 0.21-8.58 | 0.76 | 0 | Fix |
a
Peto’s OR; RCTs, randomized controlled trials; MD, mean difference; OR, odds ratio; RR, relative risk; CI, confidence interval; I 2 , statistical heterogeneity. According to the pre-defined rules, the meta-analysis results of all RCTs were used to draw conclusions for each outcome.