Jessica had arrived at the hospital on Tuesday night to have her labour induced - but Jennifer then went into labour and delivered her baby first!
Jennifer had a daughter who she named Adalynn Rose. The little girl was born with a collapsed lung, but is now said to be doing well.
A few hours later, her sister Jessica delivered her son, Mason Douglas, via Caesarean section.
The women, who live in Judah, Indiana, said it was 'kind of cool' to have their babies at the same time, but insisted they had not planned to be pregnant together, saying 'it just happened.'
"It was like, 'I'm pregnant,'" said Jessica. "I found out a week later," added Jennifer.
The women are both single mothers and have shared an apartment for the last three years.
They say they will continue to live together now they have their babies:
"It's gonna be a crazy house," said Jessica. "I hope they grow up really close."
Did you have a baby at the same time as your sibling? We'd love to hear from you below...