Depression really can start in the womb as babies are influenced by their mother’s mental state, new research showed.
A study of more than 100 British families found one year-old infants whose mothers had the blues during pregnancy had higher levels of a stress hormone.
The finding adds to a growing body of evidence that women can pass on the mental illness to their unborn baby.
Senior author Carmine Pariante, professor of biological psychiatry at King’s College London, said: ‘We already knew children born to mothers who were depressed during pregnancy are more at risk of developing depression themselves when they reach adulthood, and this paper identifies one important biological mechanism that could explain this effect.’
Her team said the physiological impacts of depression on pregnant mothers may affect babies while in the womb and lead to changes in their behaviour and biology.
Babies born to mothers who were depressed during pregnancy showed altered behaviour soon after birth compared to those of healthy mothers.
They also showed biological changes in response to stress at 12 months old.
The researchers found these differences were linked to depression-induced inflammation.
This could be a factor in why children born to mothers with depression have a higher risk of depression as adults.
The scientists recruited 106 women who were 25 weeks pregnant – 49 of whom had Major Depressive Disorder and the other 57 healthy – and followed them and their babies up to one year after birth.
They took blood from each woman at 27 weeks into their term to measure inflammation and assess whether depression put mothers’ bodies under pressure akin to an infection.
In addition, saliva samples were taken at 32 weeks and levels of cortisol – the main stress hormone – were measured.
Blood samples from women with depression in pregnancy showed increased inflammation.
What;s more saliva samples showed increased cortisol levels when they woke up and in the evening.
These women also gave birth an average of eight days earlier than the control group, at 39.2 weeks, rather than 40.4 weeks.
The researchers assessed the newborns’ abilities at six days old, using the Neonatal Behavioural Assessment Scale (NBAS), to assess alertness and response to stimuli such as noise and light
At less than a week old, newborn babies born to mothers with depression in pregnancy had poorer performances than the control group.
In addition, babies had the cortisol in their saliva measured during their routine immunisations at two months and one year.
Since every baby is vaccinated at the same age, the researchers used this opportunity to examine the babies’ responses to the stress of immunisation.
At one year, infants whose mothers had experienced depression in pregnancy had higher cortisol response following vaccination, indicating that they were more reactive to stress.
Crucially, the study identifies a previously unknown link between depression-induced inflammation in pregnant mothers and behavioural and biological changes in their babies.
Prof Pariante said: “Interestingly, the behavioural and biological changes in the baby are not due to mothers’ postnatal depression but uniquely to the depression in pregnancy, highlighting the importance of the in utero environment.”
First author Dr Sarah Osborne, also based at the Institute of Psychiatry, Psychology & Neuroscience at King’s College London, added: “Antenatal depression is common, however, it is also easily diagnosed and treated.
“This study highlights the importance of pregnant mothers seeking treatment for clinical depression, as it could have long-term beneficial effects for children.”
The study published in the journal Psychoneuroendocrinology follows previous research that found children whose mothers were depressed in pregnancy are more likely to develop anxiety and mood disorders.
This is due to a combination of genetic and environmental factors that changes part of the brain called the amygdala – responsible for controlling emotion and stress.
So babies can ‘contract’ depression from their mothers while they are still in the womb.
The team in Singapore looked at 157 pregnant women and found abnormal wiring in the right amygdala of infants of more depressed mothers.
Other research has shown that adults are up to three times more likely to suffer from the condition if their mother had it while pregnant with them.
It is thought that exposure to high levels of stress hormones in the womb has lasting effects on the unborn child’s brain.
Screening all pregnant women for depression – and treating those who need it – has been suggested to stop the legacy from being passed on.
The number of children in the UK suffering from depression is on the rise with nearly 80,000 affected.
In extreme cases they may turn to self-harm as a release or even attempt suicide.
Prof Pariante said there are limitations to his research as the team had a small sample study. He recommended replication in a larger sample.