This study assessed the extent to which women's preconception binge drinking, tobacco use and cannabis use, reported prospectively in adolescence and young adulthood, predicted use of these substances during pregnancy and at 1 year postpartum.

Data were pooled from two intergenerational cohort studies: the Australian Temperament Project Generation 3 Study (395 mothers, 691 pregnancies) and the Victorian Intergenerational Health Cohort Study (398 mothers, 609 pregnancies). Alcohol, tobacco and cannabis use were assessed in adolescence (13–18 years), young adulthood (19–29 years) and at ages 29–35 years for those transitioning to parenthood. Exposures were weekly or more frequent preconception binge drinking (5 + drinks in one session), tobacco use and cannabis use. Outcomes were any alcohol, tobacco and cannabis use prior to awareness of the pregnancy, after awareness of pregnancy (up to and including the third trimester pregnancy) and at 1 year postpartum.

Frequent preconception binge drinking, tobacco use and cannabis use across both adolescence and young adulthood were strong predictors of continued use post-conception, before and after awareness of the pregnancy and at 1 year postpartum. Substance use limited to young adulthood also predicted continued use post-conception.

Persistent alcohol, tobacco use and cannabis use that starts in adolescence has a strong continuity into parenthood. Reducing substance use in the perinatal period requires action well before pregnancy, commencing in adolescence and continuing into the years before conception and throughout the perinatal period.

Studying phenotypic and genetic characteristics of age at onset (AAO) and polarity at onset (PAO) in bipolar disorder can provide new insights into disease pathology and facilitate the development of screening tools.

To examine the genetic architecture of AAO and PAO and their association with bipolar disorder disease characteristics.

Genome-wide association studies (GWASs) and polygenic score (PGS) analyses of AAO (n = 12 977) and PAO (n = 6773) were conducted in patients with bipolar disorder from 34 cohorts and a replication sample (n = 2237). The association of onset with disease characteristics was investigated in two of these cohorts.

Earlier AAO was associated with a higher probability of psychotic symptoms, suicidality, lower educational attainment, not living together and fewer episodes. Depressive onset correlated with suicidality and manic onset correlated with delusions and manic episodes. Systematic differences in AAO between cohorts and continents of origin were observed. This was also reflected in single-nucleotide variant-based heritability estimates, with higher heritabilities for stricter onset definitions. Increased PGS for autism spectrum disorder (β = −0.34 years, s.e. = 0.08), major depression (β = −0.34 years, s.e. = 0.08), schizophrenia (β = −0.39 years, s.e. = 0.08), and educational attainment (β = −0.31 years, s.e. = 0.08) were associated with an earlier AAO. The AAO GWAS identified one significant locus, but this finding did not replicate. Neither GWAS nor PGS analyses yielded significant associations with PAO.

AAO and PAO are associated with indicators of bipolar disorder severity. Individuals with an earlier onset show an increased polygenic liability for a broad spectrum of psychiatric traits. Systematic differences in AAO across cohorts, continents and phenotype definitions introduce significant heterogeneity, affecting analyses.

Rates of common mental health problems (depression/anxiety) rise sharply in adolescence and peak in young adulthood, often coinciding with the transition to parenthood. Little is known regarding the persistence of common mental health problems from adolescence to the perinatal period in both mothers and fathers.

A total of 393 mothers (686 pregnancies) and 257 fathers (357 pregnancies) from the intergenerational Australian Temperament Project Generation 3 Study completed self-report assessments of depression and anxiety in adolescence (ages 13–14, 15–16, 17–18 years) and young adulthood (ages 19–20, 23–24, 27–28 years). The Edinburgh Postnatal Depression Scale was used to assess depressive symptoms at 32 weeks pregnancy and 12 months postpartum in mothers, and at 12 months postpartum in fathers.

Most pregnancies (81%) in which mothers reported perinatal depression were preceded by a history of mental health problems in adolescence or young adulthood. Similarly, most pregnancies (83%) in which fathers reported postnatal depression were preceded by a preconception history of mental health problems. After adjustment for potential confounders, the odds of self-reporting perinatal depression in both women and men were consistently higher in those with a history of persistent mental health problems across adolescence and young adulthood than those without (ORwomen 5.7, 95% CI 2.9–10.9; ORmen 5.5, 95% CI 1.03–29.70).

Perinatal depression, for the majority of parents, is a continuation of mental health problems with onsets well before pregnancy. Strategies to promote good perinatal mental health should start before parenthood and include both men and women.