According to new figures, one in 1,000 women are hospitalised in the months after giving birth because of some form of mental illness.
A study done at the University of Aarhus and published in the Journal of the American Medical Association looked at women who had been treated for conditions such as schizophrenia, depression or bipolar disorder.
It found that first-time mothers are seven times more likely to suffer from mental health disorders than those who already had children as well as being four times more likely to suffer from mental health disorders than those who already had children.
The risks were found to be particularly high in the first ten to 19 days after birth.
"This may indicate that the causes of postpartum mental disorders are more strongly linked to an altered physiological process related to pregnancy and childbirth than psychosocial aspects of motherhood," said the study's lead author, Trine Munk-Olsen.
The research speculated that disorders may be caused by alterations in hormone levels as well as other physical changes caused by pregnancy.