Winhusen 2008.

Methods	Multisite RCT (4 sites).
Participants	200 US pregnant substance users.
Interventions	3 session MET (n= 102) vs treatment as usual (n= 98).
Outcomes	Physiological primary: Urine toxicology Non‐physiological primary: Days of use alcohol/drugs. Secondary: Readiness to change (URICA).
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Used urn randomisation.
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgment.
Blinding (performance bias and detection bias) Patients and providers	Low risk	No blinding, but most outcomes were physiological and also used to validate self‐reports, and not likely to be influenced by lack of blinding.
Blinding (performance bias and detection bias) Assessors	Low risk	Insufficient information to know whether assessors were blinded. But most outcomes were physiological and also used to validate self‐reports, and not likely to be influenced by lack of blinding.
Incomplete outcome data (attrition bias) All outcomes	Low risk	14% attrition at 1 month follow‐up and 20% attrition at 3 months. Balanced. Reasons for dropout stated. ITT was performed.
Selective reporting (reporting bias)	Low risk	The published report included all expected outcomes based on the study hypotheses.
Other bias	Unclear risk	Urine samples were collected and tested for opiates, cocaine, methamphetamines, benzodiazepines, and marijuana at screening, weekly during the active phase of the study phase, and at the two follow‐up visits. The MET group used more cocaine and the TAU group used more marijuana at baseline. There were also baseline differences in age, ethnicity, education and pressure to attend treatment.