An American woman, Angie Cromar, is pregnant with two babies who were conceived almost a week apart in a case that has astounded doctors.
The 34 year-old has a rare condition known as uterus didelphys, which means she has two uteruses.
Mrs. Cromar, from Murray, near Salt Lake City, Utah, has been told she is due to have a boy and a girl. They are not twins and are due at different times.
Medical experts say the chance of conceiving in both uteruses is about one in five million.
Less than 100 people in the world are known to have “double pregnancies”.
At her first ultrasound doctors told the delivery and labour nurse that one baby was five weeks and a day old and the other six weeks and a day.
Mrs Cromar, who with husband Joel, 33, already have three children aged under eight, said she knew she had the rare uterine condition but it had not affected her other pregnancies.
Steve Terry, her doctor, said he was surprised when the ultrasound first revealed the double pregnancy.
Mrs Cromar, a nurse in the maternity unit at one of her local hospitals, has been told the babies, who are now at more than 20 weeks, are developing normally.
They will join her other children, Alex, eight, Luke, four and Sammy, two.