A sailor is suing the Department of Defence for the cost of bringing up her child after navy medical staff failed to detect her pregnancy.

Emily Hetherington, now aged 26 from Queanbeyan, NSW, is seeking damages for pain and suffering and loss of earnings, claiming if her pregnancy had been confirmed she would not have kept the child.

Victorian Supreme Court Justice Bernard Bongiorno was told on Thursday that Ms Hetherington did not find out about her condition until she was 22 weeks pregnant and by then it was too late for an abortion.

Ms Hetherington underwent a series of medical examinations on January 14, 2008, in Hobart after enlisting with the Royal Australian Navy when she had no idea she was already pregnant.

A urinary pregnancy test was conducted and found to be negative.