So here's something you probably didn't know was possible: You can get pregnant while already pregnant.
Uh... yeah. So it's rare, but it's definitely a thing that can scientifically happen, because it was recently proven by a surrogate mother from the US who became pregnant with her own child while carrying a baby for a Chinese couple.
The technical term for this very rare medical occurrence is "superfetation" which, according to the famously trusted source for all homework ever done — Wikipedia — "can occur only where there are two uteri, or where the oestrous cycle continues through" Interesting.
Jessica Allen told Inside Edition how she had first believed she was carrying twins after a routine ultrasound indicated there were two heartbeats. It's quite common to get twins following IVF procedures, after all. But it wasn't until after the birth, which took place by caesarean section, that it became clear something unusual had occurred.
Surrogate mother Jessica hadn't seen the twins after their delivery, so she was surprised to notice in a photograph sent by the biological parents of the "twin" babies prior to their return to China that one twin looked noticeably different than the other. Its skin was much lighter.
Jessica and her husband Jasper raised concerns about this, being unsure as to what had gone on, and eventually the babies underwent a DNA test where it was confirmed one of the children was biologically theirs.
"They were in separate sacks," Jasper told Inside Edition. It also turned out that Jessica and Jasper's child, a little boy they named Malachi, was approximately three weeks younger than his non-sibling-womb-buddy. He had been conceived almost a month after the surrogate baby had been implanted due to the unusual fact that Jessica had continued to ovulate.
And bizarrely, it's not actually the first time we've heard about superfetation. Last year, Australian woman Kate Hill got pregnant twice in 10 days, despite only having had sex the once. She ended up giving birth to two baby girls at the same time, but they're not twins. Crazy.
Jasper and Jessica are chuffed about their surprise arrival, and are thankful they acted on their suspicions. "We're definitely grateful he's with us," Jasper said. "He's walking, he's trying to talk. He's smart, he's goofy and we love him to death."