| Table 1. Main characteristics of the studies. | ||||
| Study | Type of study | N. total | N. dual group | N. hCG goup |
|---|---|---|---|---|
| Schachter et al., 2008 | Randomized controlled trial | 200 | 97 | 103 |
| Kim et al., 2014 | Observational. Prospective cohorts. | 120 | 60 | 60 |
| Decleer et al., 2014 | Observational. Prospective cohorts. | 120 | 61 | 59 |
| Mahajan et al., 2016 | Randomized controlled trial | 76 | 38 | 38 |
| Maged et al., 2021 | Randomized controlled trial | 160 | 80 | 80 |
| Haas et al., 2020 | Randomized controlled trial | 155 | 85 | 70 |
N: Number of patients in