New mothers in their early forties are five times more likely to suffer from depression after giving birth than their younger counterparts, new research has revealed.
Researcher Giulia Muraca, a Phd student at the University of British Columbia, believes this could be due to higher stress levels among older mothers fuelled by anxieties about their pregnancy and birth.
Age-associated health risk factors include increased risk of miscarriage, still-birth and having a child with a genetic defect such as Down's Syndrome.
Muraca also suggested concerns around maternity leave and returning to work could be contributing factors.
Speaking at the annual meeting of the American Assosiation for the Advancement of Science (AAS) in Vancouver, she said: "Anxiety during pregnancy has been found to be one of the strongest predictors of depression after childbirth.
"There is a lot of rhetoric talking about the biological risk, and that is really discomforting for women in that age group.
"We found that women [who have recently given birth] aged 40-44 have almost five times the odds of experiencing depression than women at younger age groups."
Muraca analysed the data of 8,000 Canadian women who answered a health questionnaire within five years of giving birth.
Women aged between 40 and 44 were five times more likely to have suffered depression than those aged 35 to 39.
Muraca said the study was "hugely exciting" because it pointed to "a potential high risk population that is growing, and has been for the past two decades."
She added: "We need to be able to council women and raise awareness of what the psychological consequences may be of birth timing."
Postnatal depression affects 10-15% of new mothers. Symptoms include depression, anxiety, irritability, exhaustion, insomnia, erratic appetite, loss of libido and feelings of guilt and negativity, hopelessness and lack of sociability.
The Royal College of Psychiatrists recommends the following steps to help prevent or ease the symptoms of postnatal depression.