The discovery that women are as likely to kill themselves in late pregnancy as early motherhood challenges key assumptions in the Gilfoyle trial.

Every professional in Liverpool Crown Court believed that the chances of a woman taking her life a couple of weeks before childbirth were almost non-existent.

A trial source told The Times: “There was a lot of statistical evidence that pregnant women never commit suicide. Human nature — they don’t. They might do it afterwards, postnatal depression.”

The defence had a potential witness, the pathologist Bernard Knight, who in 40 years had never encountered an adult murdered by hanging.

His report said that Mrs Gilfoyle’s hanging “shows no pathological evidence of anything other than self-suspension”. Professor Knight was never called to the box.

The defence barrister, David Turner, QC, knew that the prosecution would qoute statistics showing how rare it was for women to kill themselves in late pregnancy.

New research has found that women are as likely to kill themselves in the final six weeks of pregnancy as in the first six weeks after delivery.

Maternal suicides tended to be, like Mrs Gilfoyle, over 30, white, in stable relationships, from comfortable backgrounds and with a partner who worked.

The Confidential Enquiries into Maternal Deaths for 1997-2002 discovered suicide was the leading cause. “In some cases there appears to have been no evidence of any mental illness prior to the death by suicide or no clear understanding of the final trigger for the act of suicide.”

Mrs Gilfoyle was described to the jury as happy, bubbly, looking forward to the birth of her baby and making plans for the future.

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