Background Postpartum home visiting by nurses can benefit higher-risk families. Yet, little is known about the effects of universal services which provide care for all families including those at lowest risk (e.g. provision by health visitors-United Kingdom specialist community public health nurses). Objective It was to determine the effect of frequency of health visitors’ home visits on ‘low-risk’ first-time families’ outcomes to 8 weeks postpartum and 7 months follow-up. Design A cluster randomised controlled trial. Setting Within one health and social care managerial area in Northern Ireland. Participants First-time ‘low risk’ mothers who had given birth during 2002–2004 and were visited by a health visitor who had agreed to take part in the study, were invited to participate. In total, n = 39 health visitors were allocated to ‘intervention’ and n = 41 to ‘control’. Of n = 295 ‘low-risk’ first-time mothers who agreed to take part, n = 136 with intervention health visitors were offered six home visits 2–8 weeks postpartum and n = 159 within the control group were offered one planned visit. Methods Self-completed measures of parenting, maternal wellbeing and service use were gathered pre-intervention, 8 weeks and 7 months postpartum. The main outcome was the Edinburgh Postnatal Depression Scale (EPDS). At 8 weeks and 7 months postpartum, n = 129 and n = 115 intervention mothers, also n = 151 and n = 141 control mothers completed outcome measures. Results An intention to treat analysis was performed using multilevel modelling analysis which statistically controlled for pre-home visit outcomes, clinic attendance and antenatal contact. The intervention had no impact on most outcomes, however, it was associated with an increased EPDS score (after adjustment: 0.16, 2.36 95%CI) at 8 weeks (before accounting for outliers) but not at 7 months (−0.62,1.65 95%CI). Intervention mothers had higher service satisfaction (7.7, 21.28, 95%CI 8 weeks; 4.69, 22.71, 7 months) and were less likely to have used emergency medical services for their infants to 8 weeks (OR: 0.15, 0.85, 95%CI). Conclusion Weekly postpartum visits to ‘low-risk’ mothers had variable effects, therefore, practitioners and researchers should consider further development and application of effective, evidence based home visiting content.