Noah’s first close-ups, taken by ultrasound at seven and 10 weeks into the pregnancy, showed 39-year-old mom Rebecca Roberts and 43-year-old dad Rhys Weaver the baby they had tried for more than a year to conceive.
Then, at three months into the pregnancy, Noah suddenly had company.
An ultrasound taken at week 12 showed that Noah had an unexpected little sister — fraternal twin Rosalie.
“I got pregnant whilst I was already pregnant, which was absolutely crazy … because that’s not supposed to happen,” Rebecca said.
Called a superfetation, getting pregnant while already carrying a baby is so rare that one 2008 study found fewer than 10 recorded cases in the world.
Doctors told the couple the babies were actually conceived about three weeks apart, Rebecca said.
In Rebecca’s case, the egg was fertilized and implanted during the first ovulation, and “somehow she ovulated again during that same cycle,” [gynecologist Lillian] Schapiro explained. “Another egg was also fertilized — became another embryo — and at different times both embryos implanted in the uterus.”
Another reason superfetations are exceptional, Schapiro said, is that once the pregnancy begins, the uterus is no longer a hospitable place for implantation. That means the second embryo “must have managed to implant and grow at a stage when we would not have thought it would be able to grow.”