| Study characteristics |
| Methods |
2‐arm placebo‐controlled randomised trial. |
| Participants |
40 women were randomised in a hospital setting in the UK (date range not specified). The population comprised women with a history of 2 or more consecutive previous miscarriages and then subsequent pregnancy with cervical mucus ferning present. |
| Interventions |
2 x 5 mg tablets of dydrogesterone tablets 3 times daily, increased to 4 tablets 3 times daily if ferning persisted, no duration specified versus placebo. |
| Outcomes |
The study recorded the following outcomes relevant for this review: live birth and miscarriage (< 24 weeks). |
| Notes |
Contact with study authors for additional information: no. Additional data from authors: no. Source(s) of funding were not reported, declarations of interest were not reported. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
Sequence generation was not reported. |
| Allocation concealment (selection bias) |
Unclear risk |
Allocation concealment was not reported. |
| Blinding of participants and personnel (performance bias)
All outcomes |
Low risk |
Study participants and caregivers were blinded to treatment allocations. |
| Blinding of outcome assessment (detection bias)
All outcomes |
Low risk |
Assessors were blinded to treatment allocations. |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
Data were collected completely from all randomised study participants. |
| Selective reporting (reporting bias) |
Unclear risk |
The protocol of the study was unavailable for verification. However, this study was conducted before protocol registration became mandatory. |
| Other bias |
Unclear risk |
Source(s) of funding were not reported. |
