Family History of Psychiatric Disorders an Important Predictor of Postpartum Psychiatric Illness

Family history of psychiatric disorders, especially bipolar disorder, is an important factor in predicting postpartum psychiatric disorders, according to research published in the American Journal of Psychiatry.

Using a population-based cohort study, researchers evaluated the association between family history of psychiatric disorders and postpartum psychiatric disorders in proband mothers with and without psychiatric histories by assessing degree of relationship, type of disorder, and sex of family members.

Through Danish birth and psychiatric treatment registers, researchers evaluated familial risk for postpartum psychiatric episodes in a population-based cohort. The study included 362,462 first-time mothers in Denmark. The primary exposure was a diagnosed psychiatric disorder in a relative.

Using Cox regression models, researchers estimated hazard ratio (HR) for postpartum psychiatric disorders in proband mothers, defining postpartum psychiatric disorder as a treated psychiatric episode excluding organic mental disorders, substance abuse, and mental retardation. The primary analysis considered the postpartum period to be 0 to 6 months after childbirth. Researchers separately examined 0 to 3 months and 0 to 12 months after childbirth in sensitivity analyses. The association between postpartum psychiatric disorders and any psychiatric disorder in categorized relatives (first-, second-, and third-degree relatives) was broken down into 5 hierarchic diagnostic groups: schizophrenia, bipolar, unipolar, other mood disorders, and other psychiatric disorders. Proband mothers with and without psychiatric histories were examined separately.

Researchers found that 2603 of 362,462 (0.7%) proband mothers experienced psychiatric disorders within 6 months and 4085 (1.1%) experienced psychiatric disorders within 12 months after childbirth. The risk for experiencing a psychiatric disorder within the first 6 months postpartum was higher among proband mothers with a first-degree relative who had experienced any psychiatric disorder compared with proband mothers whose relatives had not experienced any psychiatric disorder (HR 1.45; 95% CI, 1.28-1.65). The HR was highest when mothers had a first-degree relative with bipolar disorder (HR 2.86; 95% CI, 1.88-4.35). Familial risk was increased for those who had first-degree relative with schizophrenia (HR 1.58; 95% CI, 1.27-1.95), unipolar disorder (HR 1.52; 95% CI, 1.24-1.87), or other mood disorder (HR 1.78; 95% CI, 1.03-3.06), but not other psychiatric disorders (HR 1.78; 95% CI, 0.70-1.16). Point estimates were larger for mothers with no previous history of psychiatric disorders. The familial risk for postpartum disorders in proband mothers whose mothers had psychiatric disorders (HR 1.50) was similar to that of proband mothers whose fathers had psychiatric disorders (HR 1.54). That pattern remained true across all diagnostic groups.

The study had several limitations. The data provided information about the timing of diagnosis and treatment, but not about the onset of symptoms. The data in the registry included inpatient hospital admission and outpatient psychiatric clinic records and excluded records from general practitioners. Researchers were unable to identify many older relatives, causing groupings of second- and third-degree relatives incomplete. Last, the sample size limited the researchers’ ability to subdivide their outcomes into specific types of postpartum psychiatric disorders.

Although postpartum psychiatric disorders are uniquely female events, a history of psychiatric disorders in male relatives is just as significant as a history of psychiatric disorders in female relatives. The risks are even higher for a family history of bipolar disorder. “Predicting who will experience a postpartum psychiatric disorder is a challenge but also of great importance,” the researchers wrote. “When assessing risk for postpartum episodes, clinicians should inquire about family history of psychiatric disorders broadly and not limit discussion to postpartum psychiatric disorders or psychiatric disorders in female relatives.”

They also recommend increasing surveillance for symptoms of postpartum psychosis in the first 2 weeks after childbirth in these risk groups.

Disclosures: Dr Wray has received funding from the Australian National Health and Medical Research Council (grants 1078901 and 1087889). Dr Sullivan has received grant support from Lundbeck and has served on advisory boards or as a consultant or speaker for Element Genomics, Lundbeck, Pfizer, and Roche. Dr Meltzer-Brody has received research grant support from Janssen and Sage Therapeutics. Dr Munk-Olsen is supported by the Lundbeck Foundation Initiative for Integrative Psychiatric Research (iPSYCH) (grant R155-2014-1724). The other authors report no financial relationships with commercial interests.

Reference

Bauer AE, Maegbaek ML, Liu X, et al. Familiality of psychiatric disorders and risk of postpartum psychiatric episodes: a population-based cohort study [published online May 7, 2018]. Am J Psychiatry. doi:10.1176/appi.ajp.2018.17111184