British experts warned that hundreds of women may be losing healthy babies every year because they are incorrectly diagnosed as having suffered a miscarriage.
Modern home pregnancy tests are now so sensitive that women are discovering they are pregnant earlier - meaning many who fear they have miscarried are attending hospital at an earlier stage than in the past.
Because a hospital scan cannot detect the earliest signs of life, it may fail to pick up a present heartbeat, leading doctors to remove a healthy foetus, according to the National Institute for Health and Clinical Excellence (NICE).
As many as 400 women may be losing healthy babies every year because of a mistaken diagnosis of miscarriage.
Glasgow University's Mary Ann Lumsden - who helped to develop new guidance published by NICE Wednesday - said in more than half of those cases the misdiagnosis was the result of ultra-sensitive home pregnancy tests.