Prietl 1992.
| Methods | Quasi‐randomised trial. TIming of randomisation: once pregnancy was confirmed by rising HCG levels from day 13 to day 15 since oocyte retrieval in IVF. Baseline characteristics in each intervention group were established and deemed comparable. |
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| Participants | 120 women having undergone IVF‐ET were allocated once pregnancy was confirmed (65 control, 55 intervention). Age: treatment group mean age was 31.7 +/‐ 0.7; age range was 25 to 39. Control group mean age was 32.8 +/‐ 0.7; age range was 26 to 40. Country: Germany. Date of study: September 1989, but end time not stated. |
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| Interventions | Control group: no hormonal treatment during pregnancy. No placebo was given. Intervention group: intramuscular injection of 500 mg 17α‐hydroxyprogesterone caproate and 10 mg oestradiol valerate in an oily vehicle (Gravibinon) twice a week. Duration: from confirmation of pregnancy until the end of the 12th week of gestation. |
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| Outcomes | Miscarriage (defined as loss between 7th and 12th week of gestation, confirmed by ultrasound and decrease in HCG). | |
| Notes | Sources of funding: not stated. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | High risk | Allocation sequence was by year of birth. However, baseline characteristics in each intervention group were established and deemed comparable. |
| Allocation concealment (selection bias) | High risk | Sequence known to personnel. |
| Blinding of participants and personnel (performance bias) All outcomes | High risk | No placebo was given. |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | Detection bias is low risk since the outcome is miscarriage. The outcome measurement is not likely to be influenced by the lack of blinding. |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | 2 participants (1 control, 1 treated) were excluded due to ectopic pregnancies. |
| Selective reporting (reporting bias) | Low risk | Protocol not available but all pre‐specified outcomes were reported. |
| Other bias | Unclear risk | Sources of funding not stated. |
HCG: human chorionic gonadotropin IVF‐ET: in‐vitro fertilisation and embryo transfer