Black 2006.

Methods	Design: individually randomized Time frame: recruitment September 1997 through December 1999 Location: Baltimore, MD (USA) Sample size calculation (and outcome of focus): no mention
Participants	General with N: 181 adolescents Source: 3 urban hospitals Inclusion criteria: low income (< 185% poverty level); < 18 years old; first‐time delivery; black race; no indication of cocaine or heroin use in chart; no chronic illness that would interfere with parenting or adolescent development; infant was term (≥ 37 weeks) and > 2500 g; infant had no congenital problem, chronic illness, or disability
Interventions	Study focus: delaying second births; parenting, contraception Theory or model: primarily Social Cognitive Theory Treatment: home‐based curriculum for adolescent mothers, maximum of 19 lessons; participants seen twice per month until infant's first birthday. Intervention included information about access to birth control; condoms provided at each visit. After first 2 visits, facilitators could vary order of sessions, as well as combine or repeat them. Comparison or control: usual care Duration: maximum of 19 visits for intervention group at 2 per month
Outcomes	Primary: second birth (not pregnancy); contraceptive use (report presented by second birth rather than randomized group) Secondary: NA Follow‐up assessments: 6, 13, 24 months
Notes	2008: unable to obtain information from investigator about contraceptive use by study arm
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	'Randomization procedure' stratified on maternal age and child's gender
Allocation concealment (selection bias)	Unclear risk	No mention
Blinding of participants and personnel (performance bias) All outcomes	High risk	Presume no blinding of participants; not feasible due to type of intervention
Blinding of outcome assessment (detection bias)	Unclear risk	No mention
Outcome measures	Unclear risk	Second birth assessed at home visit (low risk); contraceptive use reported by second birth and not randomized group (high risk)
Incomplete outcome data (attrition bias) All outcomes	High risk	Loss to follow‐up: overall, 18%; by group, intervention 20% (17/87); control 16% (15/94) Exclusions after randomization: excluded from analysis 32 mothers who did not have 24‐month evaluation (17 treatment and 15 control), because intent was to assess second births. May have had 6‐month or 13‐month evaluations.
Other bias	Unclear risk	Analysis for cluster randomized trial: NA