Johnston 2004.

Methods	Non‐randomised controlled trial.
Participants	Pregnant women of less than 22 weeks' gestation receiving care from a participating clinic; younger than 45 years, English speaking, and planning to use a study clinic for paediatric care.
Interventions	Intervention: Healthy Steps for Young Children programme (HS) beginning prenatally (PP + HS) or postnatally (HS). HS consists of risk reduction activities and universal components, including developmental screening, anticipatory guidance, and follow‐up services offered to all families receiving care. HS participants received postnatal home visits, developmental advice and parent‐initiated telephone support, developmental assessments conducted in tandem with scheduled well‐child care, the Reach Out and Read literacy program, and other risk‐based screening services and parenting classes delivered by HS specialists. PP participants also received three home visits when they were at approximately 20, 27, and 34 weeks' gestation. PP participants received home visits to help parents create a safe, knowing, and welcoming environment for their newborn, and screening and intervention for targeted risk factors such as smoking, depression, and domestic violence. Control: usual paediatric care.
Outcomes	Safety practices including safe sleep practices and Home Safety Index comprising items on car seat use, safe storage of firearms, functioning smoke detector, scald prevention activities, and safe infant sleeping practices. Results at 3 months postpartum.
Notes	Selection bias: allocation to treatment groups not described. Detection bias: unclear whether outcome assessors were blinded to treatment group. Attrition bias: At start of study: Intervention arm n = 304 (PP + HS = 151, HS = 152). Control arm n = 136. At 3‐month follow‐up: Intervention arm n = 275 (PP + HS = 139 (92.7%), HS = 136 (90.1%)). Control arm n = 121 (89.7%). Later follow‐up described in Johnston 2006. At 30‐month follow‐up, follow up of intervention arm PP + HS = 122 (81%), HS = 117 (77%). Control arm = 104 (76%).
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation to intervention/control (selection bias)(For non randomised and CBA studies)	Unclear risk	Does not report how intervention and treatment clinics chosen.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants and personnel not blinded. Participants may have been unaware of control/intervention clinics as clinics were geographically distant.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Follow‐up rate of 91% at 3 months. At 30‐month follow‐up, follow‐up of intervention arm PP + HS = 122 (81%) , HS = 117 (77%). Control arm = 104 (76%).
Selective reporting (reporting bias)	Low risk	Does not appear to be selective reporting.
Other bias	Low risk	Intention‐to‐treat analysis undertaken.
Risk of bias due to confounding (For non randomised and CBA studies)	High risk	Distribution of confounders was assessed between treatment arms, and significant differences were noted between arms on maternal education and age.