Twin Baby Girls Born On Same Day As Older Twin Sisters; Odds Are 1 In 4.5 Million

A set of twin baby girls were born on the same day as their older siblings, who are also a pair of twin sisters. The odds of this happening in one family is one in about 4.5 million but the babies' birth actually took place because their mom was induced.

Scottish mom Zoe Sullivan, 38, and her husband Ben Sullivan, 42, were not expecting the twin baby girls on Jan. 25, 2016. They were planning out fraternal twins' Charlotte and Isabelle's eighth birthday. Babies Erin and Leah were not due until April but because of pregnancy complications, the twins had to be induced, according to Closer.

Zoe went to the hospital on Jan. 23 but after an exam with her doctor, she learned that there was a problem. "Erin wasn't growing in the womb and doctors were concerned, so decided I should be induced early," the mom said, according to Mirror. "By sheer coincidence, they were then born two days later on Charlotte and Isabelle's birthday," she added.

After the babies were born, Erin needed to be transferred to another hospital because it had more facilities to help with her sepsis. The newborn twins got an all clear from their hospitals after a few more weeks -- six weeks for Leah and 10 weeks for Erin.

Last January, the two pairs of twins in the family had a big birthday bash as Erin and Leah turned one and Charlotte and Isabelle turned nine. "We had a big day for them all and did more on the weekend," Zoe said. The Sullivans now think they should prepare ahead for Jan. 25 as it's going to be an expensive four-way birthday bash for years to come.

The Sullivans have five other children -- Elizabeth, 11, Olivia, 10, Noah, seven, Evangeline, five, and Tobias, four. The kids have told their parents they also want baby siblings born on their birthdays. According to Metro, the odds of twins being born on the same day as another twin from the same parent is one in 4,562,500.