Add this to your list of fun facts to keep up your sleeve: It's possible to get pregnant while you're already pregnant, according to Live Science. Jessica Allen, a 31-year-old living in Perris, California, just learned this firsthand.
She explained to The New York Post that she was pregnant for six weeks while serving as a surrogate for another couple when she learned she had twins. She assumed they were both from the parents she was a surrogate for.
When she gave birth, she didn't see the kids because they were on the other side of a screen. But after they got back to the couple, the Lius, the mom sent a photo of them and asked Allen, "They are not the same, right?... Have you thought about why they are different?"
After the kids got DNA tests, Allen learned that one of them had the Lius' genetic material and the other one had hers and her husband's. The Lius returned this boy, Max, to the surrogacy agency and asked Allen for £14,000-19,000. The agency was offering him to parents who were willing to pay this money. Horrified by this arrangement, Allen took in Max herself instead and got a lawyer to prevent her from having to pay the fee.
What Allen experienced is called superfetation, according to Live Science. It occurs when the processes that normally shut down ovulation during pregnancy aren't working. This results in babies who are of different ages and could even have different parents, like the children Allen carried.
This phenomenon is very rare, Dr. Saima Aftab, medical director of the Fetal Care Center at Nicklaus Children's Hospital, told Live Science. Less than a dozen cases of superfetation have been the subjects of papers in medical journals. So, while it's possible, it's not common enough to warrant avoiding sex while you're pregnant just because you don't want twins.