She joked: "It must be the earliest sex change in history."
The mistake was compounded by the baby suffering from a genital abnormality called hypospadias. Dylan will need ops on his manhood to correct it - but his parents have been assured all will be fine.
They now have a new birth certificate naming Dylan.
Dad Andrew, a baker, said of suddenly having a son: "I'm thinking towards the day I can buy him a Scalextric."
Last night urology expert Dr Geoff Hackett confirmed: "The genitals develop later during pregnancy. When a baby is as small as this one and born so prematurely, it makes it more difficult to be certain."
Source-ANI