A rare condition causes a mother to conceive twins eight days apart.

An Aussie mum conceived her second child while pregnant thanks to a rare medical phenomenon that left her family stunned.

In a rare medical occurrence, a mother was given the surprise of her life when she became pregnant with her second daughter eight days after becoming pregnant with her first.

Jo, from Bunbury, Western Australia, was in the third trimester of her pregnancy when she learned she would be expecting two twins due to a rare occurrence known as superfetation.

 

Superfetation is when a new, second pregnancy happens during the first pregnancy, as another egg is fertilized by sperm and placed in the womb in just a few known occurrences around the world.

Because of their distinct sizes and development stages, the now 30-year-old mother was revealed to be carrying two twins with separate conception and due dates during an early examination.

 

“I had no idea it was twins,” Jo told FEMAIL. “It definitely doesn’t run in either of our families.”

Jo had to make some drastic modifications after receiving the shocking news before the big day.

To accommodate their unexpected new arrivals, the family upsized from their little three-bedroom home and even purchased a new car.

Ruby and Khloe, who are now six years old, were conceived naturally seven weeks early and six minutes apart, despite their separate due dates.

 

Jo said the birth was traumatic and the girls were in the hospital for over a month as Khloe wasn’t breathing and had to be resuscitated.

The mum of five said Ruby, who was conceived and born first, was taller until Khloe had a growth spurt.

“Ruby was bigger until they were about two or three, that’s when Khloe shot up, she takes after her father who’s 6’3”,” Jo said.

“They are polar opposites in everything but they still don’t like being away from each other.”