BackgroundThis study assessed whether a relatively newly developed Parent and Infant (PIN) parenting support programme was cost-effective when compared to services as usual (SAU).MethodsThe cost-effectiveness of the PIN programme versus SAU was assessed from an Irish health and social care perspective over a 24-month timeframe and within the context of a non-randomised, controlled before-and-after trial. In total, 163 parent-infant dyads were included in the study (86 intervention, 77 control). The primary outcome measure for the economic evaluation was the Parenting Sense of Competence Scale (PSOC).ResultsThe average cost of the PIN programme was €647 per dyad. The mean (SE) cost (including programme costs) was €7,027 (SE €1,345) compared to €4,811 (SE €593) in the control arm, generating a (non-significant) mean cost difference of €2,216 (bootstrap 95% CI -€665 to €5,096; p = 0.14). The mean incremental cost-effectiveness of the PIN service was €614 per PSOC unit gained (bootstrap 95% CI €54 to €1,481). The probability that the PIN programme was cost-effective, was 87% at a willingness-to-pay of €1,000 per one unit change in the PSOC.ConclusionsOur findings suggest that the PIN programme was cost-effective at a relatively low willingness-to-pay threshold when compared to SAU. This study addresses a significant knowledge gap in the field of early intervention by providing important real world evidence on the implementation costs and cost-effectiveness of a universal early years parenting programme. The challenges involved in assessing the cost-effectiveness of preventative interventions for very young children and their parents are also discussed.Trial registrationISRCTN17488830 (Date of registration: 27/11/15). This trial was retrospectively registered.