Rebecca Roberts was 12 weeks pregnant and at her third scan when suddenly the ultrasound technician went quiet.
“I thought something awful had happened,” Roberts, 39, told TODAY Parents.
But it wasn’t something awful. It was something incredible.
Roberts had become pregnant while she was already pregnant. The U.K.-based children’s clothing designer and her partner, Rhys Weaver, would later learn that their babies were conceived three weeks apart.
It’s a phenomenon called superfetation, and it's extremely rare. According to Dr. Lisa Thiel, a maternal fetal medicine specialist at Spectrum Health in Michigan, there are only a few confirmed cases.
"Superfetation is when a second pregnancy implants a few days or weeks after an initial pregnancy occurs. A new egg is fertilized by a new sperm," Thiel told TODAY Parents. "The reason this is so rare is because hormones are released by the woman’s body to prevent further ovulation and a thick mucous is created at the cervix to prevent any further sperm from entering the uterus at that time.
According to Dr. Ashley Roman, director of Maternal Fetal Medicine at NYU Langone Health, superfetation has been mostly seen in women who had IVF.
“When one fetus is conceived by IVF, and then a month later, a second fetus appears, doctors know that the embryo appeared after a natural cycle,” Roman explained. “With a spontaneous pregnancy, it’s a little trickier to confirm. But it can happen."
Roberts can attest to that.
Roberts recalled her own shock at learning she was expecting not just one, but two babies. Had they somehow missed a second heartbeat in an earlier scan?
“I couldn’t believe it. I was shaking so hard they had to lead me down the hall so I wouldn’t fall on the floor.”
Roberts joked she’s still wrapping her head around it
The Super Twins
Roberts gave birth to her "super twins" Noah and Rosalie when she was 33 weeks pregnant last September. Doctors induced labor because Rosalie — the surprise baby — had stopped growing properly.
Noah weighed 4 pounds, 10 ounces, while Rosalie weighed 2 pounds, 7 ounces. Noah was taken to the neonatal intensive care unit (NICU), while Rosalie was whisked to a special hospital where she spent 95 days.
“It broke my heart that they were separated. It was horrible,” Roberts revealed. “I remember holding both of them at the same time when they were reunited and thinking, ‘This is a milestone in itself.”
Today the 6-month-old siblings are inseparable.
“They have such a special bond. It’s not that they just lay together — they hold hands. They’ll reach out and touch each others faces,” Roberts gushed. “Rosalie was meant to be.”