IntroductionResearch about pregnancy-planning behaviour mostly focuses on women, even though pregnancy planning usually also concerns men. The purpose of this study was to investigate how men plan for family, and to measure their fertility knowledge after having become fathers.Material and methodsData were collected in 2014 as part of a Swedish longitudinal pregnancy-planning study. Men were recruited through their female partner one year after childbirth. Participants were asked to fill out a questionnaire about pregnancy planning, lifestyles, and fertility.ResultsOf the 796 participants, 646 (81%) stated that the pregnancy had been very or fairly planned, and 17% (n = 128) had made a lifestyle adjustment before pregnancy to improve health and fertility. The most common adjustments were to reduce/quit the consumption of alcohol, cigarettes, or snuff, and to exercise more. First-time fathers and those who had used assisted reproductive technology to become pregnant were more likely to have made an adjustment. Fertility knowledge varied greatly. Men with university education had better fertility knowledge than men without university education.ConclusionOur findings indicate that there is variation in how men plan and prepare for pregnancy. Most men did not adjust their lifestyle to improve health and fertility, while some made several changes. Both pregnancy-planning behaviour and fertility knowledge seem to be related to level of education and mode of conception. To gain deeper understanding of behaviour and underlying factors, more research is needed.