Partners can play an important role, but are often ignored in interventions targeting the prevention of prenatal alcohol use. A better understanding of the correlates of partner support to abstain from prenatal alcohol use can help to make a better use of partner support. The aim of this study was to identify correlates of this support by analysing differences between partners reporting low versus high support. An online cross-sectional study among 237 Dutch partners of pregnant women was conducted. Respondents were recruited through Dutch midwifery practices in September–October 2009. Questionnaires were based on the I-Change Model. Chi-square and t-test showed that partners reporting high support were more likely to desire their partner to abstain from alcohol use and to have received advice from their pregnant spouse or midwife that abstinence was desirable. They also had stronger perceptions that the baby would experience harm from prenatal alcohol use and that harm could be more severe, and they saw more advantages and fewer disadvantages of providing support. They also reported more influence from their social environment encouraging their support, had greater self-efficacy and had a stronger intention to support their partner during the remainder of the pregnancy compared to partners reporting low support. Health professionals may improve their alcohol advice by discussing the advantages and disadvantages of support with the partner and by encouraging couples to discuss and propose solutions for the situations in which partners find it difficult not to support alcohol abstinence. By providing an insight into important correlates of partner support, this study expands the research area aiming to reduce prenatal alcohol use.