A document with medical details of up to 78 pregnant women has been lost by staff at the Royal Free Hospital.

An appointments diary containing confidential information on women who visited antenatal clinics between January and May was lost by a midwife at the hospital in Pond Street, Hampstead.

It includes 78 women’s names, phone numbers and addresses. The hospital confirmed it also contained medical information for “some” of the patients, although it could not say how many.

One of the women said: “You put your trust in them and tell them everything about yourself. Then they go and tell us they’ve lost this hospital book.

“I don’t know what they put in there but I don’t want people to know all about my history.

“They don’t know where it’s gone and it’s left me really stressed.

“They have no idea who’s got it now and it’s just not good enough.”

The incident only came to light after the woman contacted the Ham&High. She said she was phoned by the hospital more than a week ago but had grown increasingly angry about the blunder.

The hospital has reported the data leak to the Information Commissioner’s Office and made contact with most of the women.

A spokesman said: “Only women who had antenatal clinic appointments at two specific clinics between January and May 2013 were affected.

“There were 78 women affected, of whom we have made contact with 73 to offer our apologies and assure them that we have a long-term plan in place to improve data security at our clinics using technological solutions.

“We are conducting a full review of the incident internally and have also reported it to the Information Commissioner’s Office. We are unable to comment yet on what disciplinary action may be taken, if any.”

Any women with concerns should contact the hospital on 020 7794 0500 and ask for the maternity bleep holder.