A British girl will later be able to boast that she was born on the same day as her older brother.

Baby Rosalie was actually born three weeks after her brother Noah was pregnant.

Their mother, Rebecca Roberts, first found out that she was expecting a baby. After a third medical examination, she learned that she was expecting two children.

The 39-year-old said, “The first scans found only one fetus daily Mail.

This phenomenon is called hypertrophy, meaning that the two co-existing embryos come from two different ovulation cycles.

“I didn’t even know it was possible to have children when I was already pregnant,” said Roberts.

The Superficial Extremely rare in humans. Only ten cases have been officially listed in the world.

The two babies, who are not twins, were born at 33 weeks last September in the UK.

The delivery process was speeded up due to a problem with Rosalie’s umbilical cord.

The girl only weighed 2 pounds 7 ounces while her brother weighed 4 pounds 10 ounces.

After two and a half months in newborn care, Rosalie is finally able to go home where she grows up with her brother.

Ms. Roberts is documenting this particular pregnancy on social media where you can see the height difference between the kids.

She also indicated that she underwent genetic testing to try to understand this particular pregnancy.

Doctors led her to believe that the medications she was taking for fertility could help produce a new egg when she was already pregnant.