Postpartum depression does not appear to discriminate between older and younger first-time mothers, an Australian study suggests.

Women over 37 were found to be no more likely to get depression following their first birth than younger women in a study of 541 women, 180 of which were 37 or older.

All study participants were given a questionnaire in their third trimester and interviewed four months after the birth. Eight percent of the women had major depression symptoms, which is within the average range for new mothers, researchers said.

Speculation that older mothers have more difficulty adjusting to motherhood is unfounded, says lead researcher Catherine McMahon at Macquarie University.

Still, McMahon concedes that older mothers have an increased risk of pregnancy complications, which complications have been linked to postpartum depression. In addition, she said, a woman's vulnerability to depression is greatest in midlife. There are a number of interesting questions to be explored in future studies, she said.