Should women be screened for postnatal depression? Exploring the effects of undiagnosed maternal mental health problems on child development.

Background: Evidence of a relationship between maternal postnatal depression and child development is consistently growing, but there has been no distinction between depression that is clearly diagnosed and treated, and depression that is never identified by health professionals. Previous models assessing the cost-effectiveness of screening for postnatal depression have been unable to account for child outcomes and the effects of undiagnosed maternal depression due to a lack of research in this area. Without these outcomes, screening for maternal postnatal depression is not currently considered to be cost-effective. Methods: Longitudinal survey data from the Millennium Cohort Study is used to explore the differential effects of undiagnosed and diagnosed maternal depression on child cognitive and behavioural development over time, and to re-examine whether screening for postnatal depression could be considered cost-effective once longer term child outcomes are included. Results: Depression that is undiagnosed has a substantial effect on the behavioural development of children. Children of mothers who are depressed but not diagnosed at 9 months are at least equally likely as those of mothers with diagnosed and treated depression to have behavioural problems later on in childhood. Identifying and treating maternal depression showed some short-term beneficial effect for child behavioural development up to age 5, but this was not maintained at age 7. Higher levels of persistent depression were identified in women who were diagnosed and treated for depression and this persistency was found to have an additive effect on child outcomes, with longer-term maternal mental health problems much more strongly associated with child outcomes than postnatal depression alone. Conclusions: This research highlights the limited success of current treatments for maternal depression, both in benefiting child development and providing long-term symptom remediation for mothers. As current treatments lack benefit for children over the longer-term, the recommendation that screening for postnatal depression appears not to be cost-effective remains unchanged