The report by Robertson et al (Reference Robertson, Jones and Haque2005) on the rates of recurrence of post-partum and non-post-partum psychosis in women who have experienced a previous episode of post-partum psychosis teaches us something new about the prognosis for these women. The risk of developing a subsequent non-puerperal episode is increased in women who have a family history of mental illness and is non-significantly increased for women with a personal history of illness prior to the puerperal episode. Robertson et al (Reference Robertson, Jones and Haque2005) report rates of relapse following subsequent deliveries of 57%. They did not report the effects, if any, of treatment in preventing further puerperal episodes. Prophylactic treatment was only alluded to in the discussion, where, following a listing of the side-effects associated with lithium and other mood stabilisers, it was stated that treatment should only be instituted following a ‘very careful weighing up of risks and benefits’. This apparently negative emphasis may be unintentional but is unfortunate for two reasons. First, although there are few studies in this area, the rates of recurrence of post-partum psychosis vary widely and have been as high as 90% (Reference Kendell, Chalmers and PlatzKendell et al, 1987). It is very probable that these recurrence rates vary according to whether women are actively managed with prophylactic medication. Second, clinical observations of the benefits of lithium prophylaxis in post-partum psychosis are supported by some published reports which suggest that lithium prevents recurrence in up to 90% of cases (Reference Stewart, Klompenhouwer and KendellStewart et al, 1991; Reference Cohen, Sichel and RobertsonCohen et al, 1995).

The relatively low rates of recurrence of puerperal psychosis reported by Robertson et al (Reference Robertson, Jones and Haque2005) may partly result from the now common practice of treating women prophylactically with mood-stabilising medication. For perinatal psychiatrists, the risk – benefit weighting of treatment with mood stabiliser v. no treatment in the puerperium for women who have had a prior episode of post-partum psychosis falls down very convincingly on the side of active treatment.