"The family is freaking out with joy," a source told E! News. "What an amazing coincidence."
Kourtney Kardashian gave birth to her third child on Sunday
The mother-of-three first revealed the pregnancy back in June to her partner's dismay. Scott's stunned reaction was seen on Keeping Up with the Kardashians.
"You just keep suckering me into these kids. I can't handle all of this responsibility," said the American businessman.
"I was not planning this. Responsibility for what? You have two children,' replied Kourtney. "I just can't take care of more kids,' said Scott.
The couple have a son, Mason, 5, and a daughter named Penelope, 2
Later the 31-year-old came round to the idea, saying he needed to "relax and enjoy the third time around" and adding that the other children had been "an amazing blessing".
The 35-year-old reality star later admitted to the cameras that she'd struggled to tell him about her third pregnancy.
"I definitely had to build up the courage to tell Scott because he has been just super depressed and I don't want to set him off."
They new addition to the family was born on Mason's fifth birthday
It's been a difficult year for the couple who mourned the loss of Scott's father in January passed away – just three months after the death of his mother.
This seems to have tipped the 31-year-old into a downwards spiral of partying which even led to him being treated for alcohol poisoning in June.
The duo then spent the summer in the Hamptons near where Scott grew up to help him regroup.