Kate and Pete Hill call their daughters “little miracles.” And with good reason. Last year, Charlotte and Olivia were conceived 10 days apart — meaning Kate got pregnant while she was already expecting. The baffling medical phenomenon, which is called superfetation, is so rare that there are only about 10 reported cases in the world. It occurs when a woman continues ovulating after conceiving, and the second fertilized egg is able to implant itself in the lining of the womb.
When the Brisbane, Australia–based couple learned what had happened, they jumped on their phones and began Googling. After all, they had intercourse only once during during that time period. “We were shocked, scared and excited all at the same time,” Kate, 34, tells Us Weekly. “Throughout our pregnancy we were constantly worried about their growth and how much smaller baby No. 2 would be.”
Though Charlotte and Olivia were given two different due dates, December 20 and December 30, both were delivered on November 29. Charlotte weighed in at 4.23 pounds, while Olivia tipped the scales at 5.46 pounds.
Hill and her husband of four years say that while Olivia generally hits milestones before Charlotte, Charlotte is never far behind. “Olivia has taken her first steps,” Kate tells Us, “and Charlotte is nearly there.”
Meanwhile, the two sisters couldn’t be more different. “Olivia is very inquisitive and loud and loves to be swung around,” says Kate. “Charlotte is a little more cautious when it comes to exploring things.”
But there is one thing Charlotte and Olivia can both agree on: Disney. “We’re having a Minnie Mouse–theme birthday party,” Kate tells Us. “They love Minnie!”
Dr. Jason James, medical director at Miami’s FemCare Ob-Gyn, called superfetation “exceedingly rare” in a November 15 interview with SELF. “Most doctors believe alleged reports are primarily due to markedly unequal growth and development of twin fetuses of the same age.” But Dr. Michael Cackovic, a maternal-fetal medicine physician at The Ohio State University Wexner Medical Center, noted that while “one episode of intercourse with two pregnancies 10 days apart is highly suspect … as they say in Jurassic Park, ‘life finds a way.’”
