Does the experience of being pregnant, giving birth and becoming a mother affect women's mental health over their reproductive life course? Much of the research on maternal mental health has focused on the perinatal period. In recent times, research has extended to patterns of women's mental health over the years following the birth of their baby. In this thesis, associations between women's experiences around pregnancy and giving birth, and patterns of their mental health impairment in the years following the baby's birth, are examined.Participants: Three datasets were used for this thesis. The primary dataset was the Mater and Methods: Six studies are the core contribution of this body of research. These studies, five cohort studies and one cross-sectional study, addressed the thesis' aims and objectives.Studies' outcome measures generally related to women's mental health, rated by the Delusions-Symptoms-States-Inventory: state of Anxiety and Depression (DSSI/sAD) (Bedford et al., 1976) and assessed at time-points post-birth. In three studies, women's DSSI depression measures at various time-points were combined to create depressive-symptoms trajectories. The Mental Disorder Screening Tool (MDST), constructed from women's DSSI/sAD responses (Saiepour et al., 2014) and measuring mental health impairment, was an outcome measure for one study. Another study's outcomes were based on women's reported alcohol consumption before pregnancy and at their first clinic visit. A broad range of predictor and potential confounding variables, taken at different MUSP survey phases, were included in the studies' analyses. Descriptive and inferential analyses were used. Univariate and multivariable regression analysis derived odds ratios and relative risk ratios with 95% confidence intervals. Pregnancy and birth events were found to contribute little to women's experience of depression. Pregnant women who experienced stressful life events (that is, financial, housing and relational events), were at higher risk of having depressive symptoms over the 27-year period. The proportion of women with mental health impairment was higher at 21 years post birth than at six months post birth. Women whose offspring had behaviour problems were themselves at risk of mental health impairment at 21 years post birth. As well, mental health problems in pregnancy; young motherhood; not completing high school and low family income; and having poor social networks around baby's birth, and marital discord in pregnancy, predicted women's poorer mental health over time. Today's pregnant women are more likely to be older and have higher body mass indexes, more likely to be anxious but not depressed, and more are sure about wanting to be pregnant, compared to pregnant women from previous decades. Today's pregnant women are also less likely to be smokers but are more often consuming alcohol prior to pregnancy, though they substantially reduce their alcohol consumption in pregnancy. Socio-economic disadvantage and psychosocial problems in pregnancy ...