A 33-year-old Romanian woman has given birth to a son and is due to give birth to his twin six weeks later in what has been called a medical first in Romania, a doctor said Tuesday.

"This is the first time this has happened in Romania," said Elena Mihalceanu, a gynecologist at the Cuza Voda hospital in this northeastern city where the first baby was born.

In a telephone interview, Mihalceanu said the twins were conceived from the same egg in May, but had separate placentas. The mother, Maricica Tescu has two uteruses due to a congenital malformation.

Mihalceanu said there had been about a dozen similar cases worldwide.

Tescu, a landscape gardener, went into early labor at 29 weeks and gave birth normally to the boy, weighing 3.5 pounds, on Dec. 11.

The baby stayed a week in intensive care, suffering breathing difficulties. He is still in the hospital but is doing well now, said Mihalceanu.

The second twin is due to be born at full term at the end of January, Mihalceanu said. The woman already has an 11-year-old son.