Mothers of twins or triplets have almost twice the average risk of postnatal depression, a survey by the Twins and Multiple Births Association showed today.

It found that 17% of mothers who had a multiple birth experienced PND, compared with an average of 10% among all mothers. Another 18% of mothers of multiples were not sure if the feelings they had amounted to postnatal depression.

The association said a few of the women walked out on their babies but returned. Others felt alone and cried regularly. Some harmed themselves and others contemplated suicide.

The survey found that mothers who suffered PND reported less sleep and less help from family and friends than non-sufferers. They were more likely to have received poor quality antenatal care or to have developed pregnancy complications. Some of the mothers said health visitors promised to drop off leaflets about depression, but did not do so. Others said doctors advised that they could not be treated for depression while breastfeeding.

Maggie Couston, a clinical psychologist and mother of triplets, said: "The months after my triplets' birth should have been a joyful experience, but I felt exhausted and isolated. My babies were the most precious thing in the world to me, but I thought I wasn't good enough for them, and frequently thought of ending things or walking away."

Judi Linney, the association's president and a former midwife, health visitor and public health director, said: "Many families struggle because not all of the NHS is sufficiently informed and equipped to meet the challenges of multiple births and pregnancies. Simple steps like improving access to multiple-specific parent education and providing practical support during the early days would do much to promote the health and wellbeing of mothers and their babies, and we call on the government to ensure this happens."

According to the Royal College of Psychiatrists, about one in 10 new mothers develop PND, which can include feelings of helplessness or being over-anxious about the baby. Without treatment, the condition can last for months or years.

It has been found that women are more likely to suffer if they have had depression before, do not have a supportive partner, have a premature or sick baby, or lost their mother when they were a child.

The association said its findings came from a survey of more than 1,000 mothers of twins or triplets.