Depression in new mothers can change a child’s stress reactions for life

A new study further highlights the importance of a mother’s postnatal mental health on her child’s later-life psychology. In research published in February in the journal, Psychoneuroendocrinology, researchers show that 22-year-old adult children born to mothers that had experienced postnatal depression exhibited greater stress responses than those whose mothers had not been depressed.

A team of researchers led by Sarah Halligan of the University of Bath utilized a sample of mothers and children that have been followed and assessed periodically for more than two decades. It is known that children of depressed mothers are at greater risk of developing depression themselves, and previous work with this and other samples have shown that children born to mothers with postnatal depression tend to have greater baseline cortisol levels, reflecting higher levels of physiological stress. Such basal cortisol levels, however, do not show whether these individuals actually react more strongly to stressful life events than others.

This study, conducted at the University of Reading, used a standardized stressful event and measured salivary cortisol to show how each individual responds to the same stress. The task included giving a five-minute speech about themselves to an unknown audience followed by five minutes of spoken mental math (counting down increments of 17 from 2023). A total of 76 participants were assessed, half of whom had mothers with postnatal depression. Those whose mothers had postnatal depression showed greater stress responses as indicated by elevated cortisol, even after controlling for: gender, baseline cortisol levels, current depression or anxiety, history of depression or anxiety, recent negative life events, and the frequency of maternal depression.

Greater spikes in cortisol following a stressful event are typically assumed to be maladaptive and have been associated with impaired declarative memory, depressive traits, and psychological disorder. The authors are quick to point out, however, that in this sample the children born to mothers with postnatal depression reacted to stress with greater cortisol levels, but were also quicker to recover from the stressor. They speculate that these individuals may actually have a developed more “dynamic” stress-response systems, which are not necessarily bad.

Altogether, these results join others in showing the importance of maternal mental health, especially in the early postnatal period. Indeed, previous work from this same population showed that mothers with postnatal depression tended to be more withdrawn and less engaged with their children while they were infants. This may be a critical time in the development of stress-response systems, the consequences of which are observable at least 22 years later. Future work is needed to uncover the particular neurobiological mechanisms that may be at play.