Wolfson 1992.

Methods	Cluster randomised controlled trial
Participants	Participants: first‐time parent couples recruited from childbirth classes. Sex: 60 mothers; 60 fathers. Age of parents: mean 28.7 years. Unit of allocation: childbirth class. Number randomised: 25 classes (no further information); 60 couples (29 intervention; 31 control). Number used in analysis: 53 couples (26 intervention; 27 control). Country & setting: USA; single‐site; recruited from community settings; intervention delivered in the community. Inclusion criteria: parents who were expected their first child; mothers and near end of their 7th month of pregnancy; both parents between 21 and 40 years of age; married; gestational age should at least 38 weeks; birth weight 5 lb or more. Exclusion criteria: infant with gross congenital abnormality or serious health problem. Ethnicity: not stated. Baseline characteristics: education: mean 15 years (SD 2.2) mothers; mean 29.2 years (SD 3.9) fathers; duration of marriage: mean 3.6 years (SD 2.2).
Interventions	Two conditions: Behavioural parent programme; wait‐list control. Duration of intervention: 4 weeks (2 pre‐natal weekly group sessions & 2 post‐birth weekly sessions). Length of follow‐up: 10 to 11 weeks.
Outcomes	Stress (modified Uplifts & Hassles Scale). Confidence (Parental Efficacy measure).
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Trial investigators report that "study used a randomised parallel group design; a) each of 25 Lamaze classes was randomly assigned to either training or control condition; b) husbands and wives where then recruited together as couples from these assigned classes; c) to minimise group process effect and group homogeneity related to Lamaze classes, couples from the same Lamaze classes were assigned to different training group sessions and filled out forms individually; training group(n=29) and control group (n=31)” (page 43). Information reported insufficient for a judgement to be made. We requested clarification from the trial investigators, but no further information was available at the time this review was prepared.
Allocation concealment (selection bias)	Unclear risk	Information reported insufficient for a judgement to be made. We requested clarification from the trial investigators, but no further information was available at the time this review was prepared.
Blinding (performance bias and detection bias) Participants	High risk	Review authors judge that it would not be possible to fully blind participants in this type of study, and found no indication of any specific additional measures taken to reduce the risk of bias that might result from differential behaviours by participants.
Blinding (performance bias and detection bias) Personnel	Unclear risk	Information reported insufficient for a judgement to be made. We requested clarification from the trial investigators, but no further information was available at the time this review was prepared.
Blinding (performance bias and detection bias) Outcome assessors	Unclear risk	Information reported insufficient for a judgement to be made. We requested clarification from the trial investigators, but no further information was available at the time this review was prepared.
Incomplete outcome data (attrition bias) All outcomes	Low risk	There was no missing data at treatment endpoint. At follow up, 3/29 (10%) in the intervention condition and 4/31 (13%) in the control condition did not return to complete assessments. Review authors judge that numbers of and reasons for missing data were balanced between conditions.
Selective reporting (reporting bias)	Low risk	Review authors judge that the published report includes all expected outcomes, including those that were pre‐specified.
Other bias	Low risk	The study appears to be free of other sources of bias.