Post-partum psychosis: which women are at highest risk?

Background Psychotic illness following childbirth is a relatively rare but severe condition with unexplained etiology. The aim of this study was to investigate the impact of maternal background characteristics and obstetric factors on the risk of postpartum psychosis, specifically among mothers with no previous psychiatric hospitalizations. Methods and Findings We investigated incidence rates and potential maternal and obstetric risk factors of psychoses after childbirth in a national cohort of women who were first-time mothers from 1983 through 2000 (n = 745,596). Proportional hazard regression models were used to estimate relative risks of psychoses during and after the first 90 d postpartum, among mothers without any previous psychiatric hospitalization and among all mothers. Within 90 d after delivery, 892 women (1.2 per 1,000 births; 4.84 per 1,000 person-years) were hospitalized due to psychoses and 436 of these (0.6 per 1,000 births; 2.38 per 1,000 person-years) had not previously been hospitalized for any psychiatric disorder. During follow-up after the 90 d postpartum period, the corresponding incidence rates per 1,000 person-years were reduced to 0.65 for all women and 0.49 for women not previously hospitalized. During (but not after) the first 90 d postpartum the risk of psychoses among women without any previous psychiatric hospitalization was independently affected by: maternal age (35 y or older versus 19 y or younger; hazard ratio 2.4, 95% confidence interval [CI] 1.2 to 4.7); high birth weight (≥ 4,500 g; hazard ratio 0.3, 95% CI 0.1 to 1.0); and diabetes (hazard ratio 0). Conclusions The incidence of psychotic illness peaks immediately following a first childbirth, and almost 50% of the cases are women without any previous psychiatric hospitalization. High maternal age increases the risk while diabetes and high birth weight are associated with reduced risk of first-onset psychoses, distinctly during the postpartum period.
Unnur Valdimarsdóttir and colleagues studied the risk factors for psychiatric illness following childbirth and found that, for women who had never previously been hospitalized for a psychiatric illness, the risk of mental illness was greatly increased following childbirth.
Editors' Summary Background. The first cries of a new life echo around the delivery suite: this is a time of great joy for most women. Yet, in the following days and weeks (the postpartum period), up to 80% of new mothers experience some sort of mental disturbance. Usually, this is the “baby blues,” a normal reaction to childbirth that is characterized by short-lived mood swings or postnatal depression. However, about one in 1,000 women develop postpartum psychosis, a serious mental disorder that needs immediate medical attention. Postpartum psychosis usually develops suddenly in the first 2–3 weeks after delivery and, like other forms of psychosis, is characterized by a loss of contact with reality. Women with postpartum psychosis may have false ideas about current events and about themselves (delusions) and see and hear things that are not there (hallucinations). They sometimes stop eating or sleeping and may become anxious and agitated. In the worst cases, they can have suicidal thoughts or even threaten their baby's life. Treatment for postpartum psychosis includes antipsychotic drugs, counseling, and hospital admission if the woman is a danger to herself or others. Why Was This Study Done? Women with a personal or family history of psychosis have an increased risk of developing postpartum psychosis, but what causes this disorder is unknown. The rapid changes in hormone levels that occur after delivery are likely to be involved—but might social circumstances, stress, other illnesses, or the birth itself also affect whether a woman develops postpartum psychosis? If additional risk factors for postpartum psychosis could be identified, it might be possible to prevent some cases of this serious mental disorder. In this study, the researchers investigate the incidence rate (the rate at which new cases occur in a population) and risk factors for psychotic illnesses diagnosed among first-time mothers registered in the Swedish Medical Birth Registry between 1983 and 2000. What Did the Researchers Do and Find? The researchers identified three-quarters of a million first-time mothers and, from the Swedish Hospital Discharge Registry, found that 892 of these women (1.2 per 1,000 births) had been admitted to hospital because of psychosis within 90 days of giving birth. Put another way, the incidence rate of psychosis over the first 90 days postpartum in this population was 4.84 per 1,000 person-years. Almost half of the women who developed postpartum psychosis had not been previously admitted to hospital for any psychiatric disorder. Among this subset of women, the incidence rate of postpartum psychosis was highest during the first month after delivery but dropped to less than a tenth of this initial rate after 90 days postpartum. Furthermore, the risk of developing psychosis during the first 90 days postpartum (but not after) increased with age—women older than 35 years were more than twice as likely to develop psychosis than those aged 19 years or less—but was reduced in women who had large babies or who had diabetes. Many other factors (including smoking and not living with the infant's father) did not affect the risk of psychosis during the first 90 days postpartum in these women. What Do These Findings Mean? These findings indicate that the occurrence of psychotic illness severe enough to require hospitalization peaks shortly after giving birth for the first time, even in women with no previous psychiatric illness. Indeed, women with no history of mental disorders account for almost half the women admitted to hospital for postpartum psychosis, at least in Sweden. The timing of the peak of postpartum psychosis supports the idea that either giving birth or the hormonal changes that occur shortly after may trigger the development of psychosis, and the findings that maternal diabetes and high infant birth weight reduce the risk of postpartum psychosis whereas increasing maternal age increases the risk provide new clues about the causes of postpartum psychosis. Most importantly, however, these findings highlight the importance of carefully monitoring women for psychosis during the first month after delivery. Additional Information. Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000013. This paper is further discussed in a PLoS Medicine Perspective by Phillipa Hay The MedlinePlus Encyclopedia contains a page on MedlinePlus encyclopedia psychosis (in English and Spanish); MedlinePlus also provides links to information on psychotic disorders The UK National Health Service Direct Health encyclopedia has information on psychosis and on postnatal depression Mental Health America has a fact sheet on postpartum disorders