Medical rarity: Woman gives birth to babies conceived 3 weeks apart

Rebecca Roberts and her partner struggled with infertility for more than a year, so when they got a positive result with an at-home pregnancy test, they were overjoyed.

But the news did not feel real until the first ultrasound appointment, when the couple saw their baby on a sonogram screen and listened to the calming cadence of a steady heartbeat.

“I remember walking away from the very first scan so happy,” said Roberts, 39, who lives in Wiltshire, England.

But her excitement abruptly shifted to shock five weeks later at the 12-week ultrasound appointment, when the sonographer spotted something astonishing: It appeared as though Roberts was suddenly carrying two babies — one of which was considerably less-developed than the other. The room fell silent.

This was not a typical set of twins, Roberts learned. Her pregnancy was diagnosed as superfetation, a rare condition in which a woman who is already pregnant conceives another baby.

Roberts’ pregnancy is one of very few superfetation cases recorded in medical literature, said her obstetrician, David Walker.

Superfetation is so uncommon that Walker struggled to diagnose it. In his 25 years as an obstetrician, it was something he had never seen. Ordinarily, hormonal and physical changes during pregnancy prevent another conception from occurring. That was not the case for Roberts.

When he gave Roberts and her partner, Rhys Weaver, 43, the diagnosis, “it was a massive shock,” Roberts said. “We went home and got straight onto Google.”

Surfing the Web, she said, proved mostly futile because there is minimal research and there are few examples of successful superfetation pregnancies. The condition is so rare that alleged cases are sometimes met with skepticism.

Although Roberts’ children had different due dates, she had a Caesarean section and gave birth to both babies on Sept. 17. Noah came first, weighing 4 pounds, 10 ounces. Two minutes later, his younger sister, Rosalie, arrived, weighing 2 pounds, 7 ounces.

“We got to see both of them as soon as they were born,” Roberts said. “It was absolutely beautiful.”

“One of the best feelings I’ve ever had,” Weaver said.

Taking care of twins, who are now almost 6 months old, has been a whirlwind, especially during the pandemic lockdown and while working from home. But Roberts said it has made her heart full to watch the babies grow and develop over the past few months.

COURTESY OF REBECCA ROBERTS Rhys Weaver (left) and Rebecca Roberts of Wiltshire, England, pose with their twins in March. They were born two minutes apart on Sept. 17 after Roberts had a Caesarian section.