Researchers at The Kids Research Institute Australia have found daughters born to older mothers have higher rates of some mental health problems.
The researchers used data from the Western Australian Pregnancy Cohort (Raine) Study to examine more than 1200 twenty year olds, with the results published in the Journal of Abnormal Psychology.
They found daughters of mothers aged 35 and over at childbirth were at increased risk for symptoms of depression, anxiety, and stress at age twenty.
Researchers did not find the same association for sons born to older mothers.
Lead researcher Jessica Tearne, from The Kids Research Institute Australia and the UWA School of Psychology, said researchers did not yet know why this relationship existed between older mothers and daughters in particular.
She said more research was needed but one hypothesis is that the large age gap may impact uniquely on the mother daughter relationship.
"It may be that the different value systems between mother and daughter could be causing some tension in the relationship, particularly during the transition to adulthood," she said.
Ms Tearne said it was important to note that the study looked at symptoms of distress, rather than a clinical diagnosis of mental health problems.
"Our study examined self-reported symptoms of depression, anxiety, and stress, so it is plausible that the risk factors for symptoms of distress versus a diagnosed condition are different," she said.
"It could be the case that daughters of older mothers are at risk for more symptoms of depression, anxiety, and stress, but that does not necessarily mean they will receive a diagnosis or experience mental illness," she said.
"Our next step is to examine why this relationship exists between mother and daughter, and whether we can use this information to identify individuals at risk of mental health issues so we can intervene early or promote healthy relationships in families."
This paper builds on Ms Tearne's previous research looking at how parental age can impact on a child's behaviour at different stages of their development.
She suspects the impact of maternal age on a child's thoughts and feelings may change as a child grows up.
"Our research has shown that while there are many positive things about being an older mum, there may also be some associated risks. What we need to do now is work out how we can best support mums at all stages of parenting."
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Read a full copy of the results in the Journal of Abnormal Psychology here.
About the Raine Study:
The Raine Study is jointly conducted by The Kids Research Institute Australia and the University of Western Australia. The study started in 1989, when 2900 pregnant women were recruited into a research study at King Edward Memorial Hospital to examine ultrasound imaging. The mothers were assessed during pregnancy and health and lifestyle information was collected on the mother and the father. After the children were born, they were assessed at birth, at one year, then two, three and five years of age. Further follow-ups of the cohort have been conducted at eight, ten, 14, 17, 20 and now 22 years of age. Find out more here.