Summary of findings 3. Natural cycle FET versus modified natural cycle FET (HCG trigger).
| Natural cycle FET versus other regimens for primary or secondary subfertility | ||||||
| Population: subfertile women Settings: assisted reproductive technology clinics Intervention: natural cycle FET Comparison: natural cycle plus HCG trigger FET1 | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect (95% CI) | No of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Modified natural cycle FET (HCG trigger) | Natural cycle FET | |||||
| Live birth rate per woman | 267 per 1000 | 167 per 1000 (55 to 413) | OR 0.55 (0.16 to 1.93) | 60 (1 study) | ⊕⊝⊝⊝ Very low2,3 | Only 13 events |
| Miscarriage rate per woman | 24 per 1000 | 5 per 1000 (0 to 92) | OR 0.20 (0.01 to 4.13) | 168 (1 study) | ⊕⊝⊝⊝ Very low2,4 | Only 2 events |
| Ongoing pregnancy rate per woman | 107 per 1000 | 226 per 1000 (110 to 408) | OR 2.44 (1.03 to 5.76) | 168 (1 study) | ⊕⊝⊝⊝ Very low2,4 | Only 28 events |
| Multiple pregnancy per woman | No data available | |||||
| *The basis for the assumed risk is the mean control group risk across studies. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; FET: frozen‐thawed embryo transfer; GnRHa: gonadotrophin releasing hormone agonist;HCG: human chorionic gonadotrophin; HT: hormone therapy; OR: odds ratio. | ||||||
| GRADE Working Group grades of evidence High quality: We are very confident that the true effect lies close to that of the estimate of the effect Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect | ||||||
1One other study compared natural cycle FET versus natural cycle plus human menopausal gonadotrophin, but did not report any per‐woman data. 2Downgraded two levels due to very serious imprecision: single study, few events, confidence interval compatible with benefit in the modified natural cycle only or with no effect. 3Downgraded one level due to serious risk of bias: high attrition rate, baseline characteristics unequal. 4Downgraded one level due to serious risk of bias: no allocation concealment.