Identification of women at high risk of postpartum psychiatric episodes: A population-based study quantifying relative and absolute risks following exposure to selected risk factors and genetic liability

BACKGROUND

We quantified relative and absolute risks of postpartum psychiatric episodes (PPE) following risk factors: Young age, past personal or family history of psychiatric disorders, and genetic liability.

METHODS

We conducted a register-based study using the iPSYCH2012 case-cohort sample. Exposures were personal history of psychiatric episodes prior to childbirth, being a young mother (giving birth before the age of 21.5 years), having a family history of psychiatric disorders, and a high (highest quartile) polygenic score (PGS) for major depression. PPE was defined within 12 months postpartum by prescription of psychotropic medication or in- and outpatient contact to a psychiatric facility. We included primiparous women born 1981-1999, giving birth before January 1st, 2016. We conducted Cox regression to calculate hazard ratios (HRs) of PPE, absolute risks were calculated using cumulative incidence functions.

RESULTS

We included 8174 primiparous women, and the estimated baseline PPE risk was 6.9% (95% CI 6.0%-7.8%, number of PPE cases: 2169). For young mothers with a personal and family history of psychiatric disorders, the absolute risk of PPE was 21.6% (95% CI 15.9%-27.8%). Adding information on high genetic liability to depression, the risk increased to 29.2% (95% CI 21.3%-38.4%) for PPE.

CONCLUSIONS

Information on prior personal and family psychiatric episodes as well as age may assist in estimating a personalized risk of PPE. Furthermore, additional information on genetic liability could add even further to this risk assessment.

Divorce or Separation Following Postpartum Psychiatric Episodes: A Population-Based Cohort Study

Objective: Psychiatric disorders are an established risk factor for divorce or separation. Despite the fact that 10%-15% of new mothers experience postpartum psychiatric episodes (PPEs), no previous studies have investigated the effects of PPEs on the probability of divorce in these new families. Therefore, this study aimed to investigate and quantify the probability of subsequent divorce/separation among women with either mild/moderate or severe PPE compared to mothers without PPE. Methods: This cohort study based on the national Danish registers included all cohabitating, primiparous women without previous psychiatric history who gave birth from 1996 through 2014. At 6 months postpartum, each woman's PPE status was evaluated and categorized as follows: (1) mild/moderate PPE (prescription of psychotropic medication-Anatomical Therapeutic Chemical Classification codes N03-N07), (2) severe PPE (psychiatric inpatient or outpatient treatment-International Classification of Disease, 10th Edition codes F00-F99, excluding codes for organic mental disorders, substance abuse, and mental retardation), and (3) no PPE (reference group). Subsequently, the status of cohabitation was assessed a maximum of 5 times (every January 1). Results: A total of 266,771 new mothers were included; 4,442 had a first mild/moderate PPE and 1,141 had a first severe PPE within 6 months postpartum. Compared to mothers without PPE, women with mild/moderate PPE had a significantly higher probability of later divorce (adjusted hazard ratio [HR] = 1.23; 95% CI, 1.15-1.31); for women with severe PPE, the probability was even greater (adjusted HR = 1.64; 95% CI, 1.45-1.85). Conclusions: Women experiencing their first-ever PPE following childbirth have a higher probability of divorce in the years following their diagnosis than mothers without PPE. Further, this study showed a dose-response relationship between the severity of PPE and the probability of divorce.

General medical conditions and mortality in women with postpartum psychiatric disorders

BACKGROUND

Psychiatric patients have an increased risk of general medical conditions and mortality, but no study has systematically explored these outcomes among women with mental disorders following childbirth (postpartum psychiatric disorders: PPD). Therefore, we aimed to investigate the risk of subsequent general medical conditions and mortality in women with a broad spectrum of PPD.

METHODS

This register-based cohort study followed all Danish women born after January 1, 1960, until January 1, 2016. The exposure of interest was (i) mild-moderate PPD: first-ever prescription of psychotropic medication (ATC codes: N03-N07) and (ii) severe PPD: first-ever in- or out-patient contact to a psychiatric facility, both within six months postpartum. Outcomes of interest were (i) hospital-registered chronic medical conditions and (ii) mortality from natural and unnatural causes. We included 1 841 949 women representing 22 615 310 person-years at risk.

RESULTS

Among 15 852 women with mild-moderate PPD and 4266 women with severe PPD, we found a higher risk of any subsequent general medical condition (mild-moderate PPD: IRR 1.25; 95% CI 1.20-1.31 and severe PPD: IRR 1.35; 95% CI: 1.24-1.48) when compared to the female background population. Mortality from both natural and unnatural causes was higher in both groups: Mild-moderate PPD: natural causes MRR 1.37; 95% CI: 1.17-1.61; unnatural causes MRR 1.52; 95% CI: 1.10-2.11, and severe PPD: natural causes MRR 1.42; 95% CI 1.02-2.00, and unnatural causes MRR 5.05; 95% CI: 3.40-7.51.

CONCLUSIONS

This first overview of general medical prognosis in PPD shows that women at either end of the spectrum are at increased risk of subsequent chronic medical conditions and overall mortality.

Genetic risk scores for major psychiatric disorders and the risk of postpartum psychiatric disorders

Postpartum psychiatric disorders are heritable, but how genetic liability varies by other significant risk factors is unknown. We aimed to (1) estimate associations of genetic risk scores (GRS) for major depression (MD), bipolar disorder (BD), and schizophrenia (SCZ) with postpartum psychiatric disorders, (2) examine differences by prior psychiatric history, and (3) compare genetic and familial risk of postpartum psychiatric disorders. We conducted a nested case-control study based on Danish population-based registers of all women in the iPSYCH2012 cohort who had given birth before December 31, 2015 (n = 8850). Cases were women with a diagnosed psychiatric disorder or a filled psychotropic prescription within one year after delivery (n = 5829 cases, 3021 controls). Association analyses were conducted between GRS calculated from Psychiatric Genomics Consortium discovery meta-analyses for MD, BD, and SCZ and case-control status of a postpartum psychiatric disorder. Parental psychiatric history was associated with postpartum psychiatric disorders among women with previous psychiatric history (OR, 1.14; 95% CI 1.02-1.28) but not without psychiatric history (OR, 1.08; 95% CI: 0.81-1.43). GRS for MD was associated with an increased risk of postpartum psychiatric disorders in both women with (OR, 1.44; 95% CI: 1.19-1.74) and without (OR, 1.88; 95% CI: 1.26-2.81) personal psychiatric history. SCZ GRS was only minimally associated with postpartum disorders and BD GRS was not. Results suggest GRS of lifetime psychiatric illness can be applied to the postpartum period, which may provide clues about distinct environmental or genetic elements of postpartum psychiatric disorders and ultimately help identify vulnerable groups.