Women are more likely to become depressed during pregnancy than after their child is born, according to new research publishedy.

Women are more likely to become depressed during pregnancy than after their child is born, according to research published today.

A study of more than 9,000 women, published in the British Medical Journal, found the peak point for depression was in the 32nd week of pregnancy. It suggests that the focus on post-natal depression may be misguided and that pregnant women should be screened for depression.

About one in 10 women are estimated to suffer from postnatal depression, although campaigners say up to a third may fall victim to the condition. It can lead to neglect of the child, family breakdown and suicide, and cause behavioural problems in the children of depressed mothers.

The broadcaster Esther Rantzen, the model Jerry Hall and the Coronation Street actress Denise Welch are among the celebrities who have suffered post-natal depression. Recognition of the condition has improved in recent years, and GPs, health visitors and community midwives are now trained to spot the symptoms.

But experts believed that pregnancy could actually protect against depression, and the problems of antenatal depression were played down.

Researchers from the University of Bristol asked more than 9,000 women in the Avon area who were due to give birth in 1992 to complete a questionnaire on their emotional state at 18 weeks and 32 weeks into pregnancy. They were also asked to complete questionnaires on their emotional state at eight weeks and eight months after the birth.

The researchers found that at 18 weeks of pregnancy, 11.8 per cent of the women registered above the threshold for "probable depression". That rose to a peak of 13.5 per cent at 32 weeks, as women were in the last stages of pregnancy.

Eight weeks after the birth, 9.1 per cent were calculated to be suffering from probable depression, falling to 1.6 per cent eight months later. The biggest rise in the number of mothers suffering from depression came between 18 and 32 weeks of pregnancy.

Jonathan Evans, the lead investigator, said: "Our results show depression during pregnancy is more common than post-natal depression. Offering treatment may be important both for the mother and the future well-being of the child and family. It is also important to study the potential benefits of screening for, and treating depression during pregnancy."

Depression during pregnancy has been linked to low attendance of clinics, low birth weight and premature birth.