A Brazilian woman with two wombs has given birth to healthy twins - one from each womb.
Doctors had to perform a caesarean section four weeks before the full 40-week term, but said the non-identical twins - a boy and a girl - and their mother were fine.
It is extremely rare for foetuses to develop normally and symmetrically in women with two wombs, doctors say.
"The twins are perfectly normal and there is an excellent prognosis for their development," said Ivan Lima, director of Meridional Hospital in Cariacica, Espirito Santo state, where they were born.
"No cases of twins being born from two separate uteri have been described in Brazilian medical literature," he said, according to news agency Reuters.
Having each developed from a separate egg, the twins are genetically only as similar as any other brother and sister.
About one in a thousand women are said to possess double wombs, but few ever bring simultaneous pregnancies in both to full term.
Some women with two wombs also have two cervixes and two vaginas.
Most are able to have children, though may need additional medical attention close to the end of pregnancy.
A Chinese woman with two wombs gave birth to two healthy babies last November, according to Chinese news agency Xinhua.
It quoted Shang Zhifan, head of Mudanjiang Maternity Hospital, as saying there were previously six recorded instances of such double pregnancies in China.