Parenting website Mumsnet is investigating after a data breach on the site that let some people see details of other accounts.
In a statement it said the problem occurred between 2pm on Tuesday and 9am on Thursday.
During this time some account holders who logged in at the same time had their account information switched and were able to inadvertently access each other's details.
Approximately 4,000 people were logged in during the breach period.
However, the site has now stated the total number breached was 44.
Email addresses, account details, posting history and personal messages may have been accessible as a result, Mumsnet said, but confirmed passwords were safe as that data is encrypted.
It is believed that a "software change, as part of moving our services to the cloud", may have been the cause of the problem.
The firm has since reversed the change and said it has not been aware of any further incidents.
A spokeswoman for the site said: "We're very sorry to say that we’ve become aware of a data breach which affected some Mumsnet user accounts."
Previously, a statement said: "We know some of you will be very worried by the possibility that your account has been breached - please mail us on contactus@mumsnet.com if you'd like to discuss your individual account details."
The website confirmed it would report the incident to the Information Commissioner's Office (ICO), which said in a statement it had been made aware of the incident and will be "considering the detail".
