Mistaken NHS statistics accounts to tens of thousands of 'male mums' in Britain.
The finding, far from being a one-off, is just one of a range of bizarre results discovered by doctors who have examined NHS hospital data.
They discovered that 17,000 men were recorded as having been admitted to hospital for obstetric services - a specialisation for pregnant women and their babies - and 8,000 to see a gynaecologist; while another 20,000 apparently needed to see a midwife.
They also identified a steady increase in the numbers of children and teenagers attending geriatric services, to over 3,000 between 2009 and 2010, and more than 1,600 adults over 30 using child psychiatry services, the Telegraph reported.
The mistakes are due to human error, with those inputting the details striking the wrong key and recording a patient as having used a part of the NHS that they did not.
The four doctors, who work for Imperial College Healthcare NHS Trust in London, have written a letter about the errors, discovered in Hospital Episode Statistics (HES) data, to the British Medical Journal.
In it they warn that if such mistakes are widespread, but it is assumed the data are accurate, there could be serious negative consequences for reforming the NHS.
The authors of the letter joked that perhaps this was part of an innovative exchange programme.
However, they said that in seriousness fellow doctors should "all examine the data being submitted by and about our services for unintentional innovation".