BackgroundMood and anxiety and related disorders (AD) account for a significant proportion of mental health conditions, with close to 30 % of the population (28.8 %) suffering from an AD at some time in their life, and over fifteen percent (16.2 %) suffering from a mood disorder. The existing empirical literature leaves a number of important gaps with respect to our understanding of mood, anxiety and stress related difficulties among pregnant and postpartum women. The objective of this research is to address these.MethodsParticipants were 660 English-speaking pregnant women. Participants for the portion of the research estimating the prevalence/incidence of perinatal mood disorders and AD (N = 347) were recruited proportionally from a geographically defined area. All participants were recruited via prenatal clinic visits at hospitals, physician offices and midwifery clinics, and via community outreach at events and through word of mouth. Recruitment took place between November 9, 2007 and November 12, 2010. Participants were administered questionnaires prenatally at two time points (approximately 24 and 33 weeks gestation) and again at 4–6 weeks’ postpartum and 6-months postpartum. Prevalence/incidence study participants who screened above cut-off on one or more of the 4–6 week mood and anxiety questionnaires were also administered a diagnostic interview for mood disorders and AD at approximately 8–12 weeks postpartum.DiscussionThis research addresses a number of gaps in our understanding of mood, anxiety and stress among pregnant and postpartum women. Specifically, gaps in our knowledge regarding the prevalence and incidence of (a) AD and mood disorders, and (b) anxiety and stress among women experiencing a medically high-risk pregnancy, interest in stress management training in pregnancy, mental health treatment barriers and access and screening for anxiety among pregnant and postpartum women are addressed. The findings from this series of studies have the potential to improve screening, assessment and treatment of mood and anxiety problems suffered by pregnant and postpartum women.