Date Published: February 10, 2009
Publisher: Public Library of Science
Author(s): Phillipa J Hay
Abstract: Phillipa Hay discusses the implications of a new study of psychotic illness and its risk factors up to 90 days postpartum in first-time Swedish mothers.
Partial Text: A range of psychological disorders occur in women in the post-partum period. These include “the blues”, which occurs in the first days after birth and which is very common and self-limiting; severe psychoses often associated with mania or bipolar illness, occurring in the first weeks after birth ; and mild to moderate depression, occurring weeks to months after birth.
In a new study published in PLoS Medicine, Unnur Valdimarsdóttir and colleagues have investigated the clinical incidence of psychotic illness and its risk factors up to 90 days post-partum in a large case register study of first-time Swedish mothers . This study investigates an important problem, since the effects of maternal psychosis on attachment and infant care in the post-natal period can have lifelong adverse sequelae for mother and child . The researchers argue correctly that whilst previous psychiatric illness is a well known risk factor for post-partum psychosis, it is not known how much other independent risk factors, such as obstetric complications, may be relevant. Only by studying first-time mothers with first psychotic episodes in the post-partum period can these independent risk factors begin to be elucidated.
The authors correctly recognise that their findings cannot determine why the risk of psychosis is highest in the first month after birth. They postulate several explanations, favouring a biological vulnerability due to the profound hormonal fluctuations, particularly falls in estrogen levels, in this period. There is some empirical support for this hypothesis, to the degree that estrogen replacement has been proposed as a potential therapeutic agent in treating schizophrenia, with preliminary albeit inconclusive and mixed support from controlled trials [4,5]. However, as the authors report, a controlled trial found no support for the use of estrogen to prevent psychosis after childbirth . Valdimarsdóttir and colleagues propose several hypotheses to explain the protective effects of diabetes and the greater risk in older mothers and those with infants of lower birth rate. They suggest that the risk factors may be mediated by greater estrogen depletion post-partum. However, the possibility that these may be proxy risk factors associated with some other more direct factor needs to be considered .
Previous psychiatric illness remains an important risk factor for post-partum psychosis (as shown in the authors’ previous work ), the treatment of post-partum psychosis is largely with anti-manic agents , and the future risk of bipolar disorder outside the post-partum period is high . Nevertheless, there is some empirical support for regarding first-time post-partum psychosis as distinct from post-partum psychosis where there is a history of previous psychosis.
The new study raises important questions for future research . To determine pathways to psychosis, and which risk factors are proxy, overlapping, truly independent, mediating, or moderating , there need to be targeted empirical prospective studies of new mothers at high risk and/or identified early in the post-natal psychosis. Such prospective studies would also enable delineation of the temporal sequence of putative biological but also social and demographic variables.