Postnatal depression which persists beyond six months after birth and is severe, increases the risk of children exhibiting behavioural problems, achieving lower GCSE mathematics grades at sixteen years old and having depression at eighteen years old. Postnatal depression which is persistent (whether moderate or severe) increases mothers’ risk of continuing to experience depressive symptoms beyond the postnatal year, with high levels found up until eleven years after childbirth.

Available research suggests that postnatal depression is associated with increased risks to children’s development affecting a range of domains. The effects are variable with some evidence suggesting that brief episodes, while distressing to the mother, may not impact negatively on children’s development. However, episodes of depression which persist for six months or more in duration may increase the risk for children. Identifying women at most risk is important both for women’s mental health and children’s development. The University of Bristol reports the authors investigated whether depression has a similar impact when it is, or is not, persistent at either moderate or severe levels. Researchers from the Universities of Oxford, Bristol, Reading and UCLA, in a new paper in JAMA Psychiatry, tracked changes in mothers’ depressive symptoms following the postnatal year and differences in children’s development when postnatal depression was, or was not, persistent.

The sample consisted of 9,848 mothers and 8,419 children who were taking part in the Avon Longitudinal Study of Parents and Children (ALSPAC). The study utilises data from different stages of children’s development ranging from preschool to late adolescence including behaviour problems at 3.5 years old, GCSE maths grades at sixteen years old and depression at eighteen years old to determine potential effects both in the short and long term.

The study highlights for the first time that when postnatal depression is both persistent and severe the risk of negative outcomes to children’s development is raised. Furthermore, when depression persists beyond the first six months after birth, the risk for mothers continuing to experience depressive symptoms beyond the postnatal year is also increased. The authors report that these symptoms can continue up to eleven years after childbirth, but it is possible that they persist even longer. For two of the outcomes (GCSE maths grades at sixteen and depression at eighteen), when postnatal depression either did not persist, or persisted only at moderate severity, the odds of achieving lower GCSE mathematics grades or experiencing depression at eighteen years old were similar to those of children whose mothers did not experience depressive symptoms at all in the postnatal year. This suggests that long term negative effects on maths grades and depression in adolescence principally occur in the context of persistent depression, but not with briefer and/or less severe episodes.

The study identifies a group of mothers and children who should be prioritised for treatment both to address maternal depression that is more likely to continue, and to mitigate the effects on children’s development. The authors have recently shown that treatment for women with persistent postnatal depression can be delivered effectively with high rates of sustained remission using home-based delivery of a psychological therapy.

Dr Elena Netsi from the Department of Psychiatry at Oxford University and lead author on the paper said “Depression which persists beyond the first 6 months after birth should alert health care professionals to a depression which may become chronic. While screening for postnatal mental health problems in the UK already occurs within the first 3 months, screening once more in the second part of the postnatal year will help identify families who should be prioritised for treatment, both to address the mother’s depression and to mitigate potential effects on children’s development. Given that there are effective psychological therapies for depression it is important that help is provided for these women.”