Rebecca Robertson is a British woman who became pregnant with two babies, but during pregnancy reviews they noticed something very rare: that one of the babies was three weeks smaller than the other.
How is it possible? It is what is known as superfetacion, or getting pregnant while already pregnant . It is such a strange phenomenon that there are only 14 documented cases worldwide, including this one.
The mother told the Mirror newspaper that she had an ultrasound at seven weeks and was told she was expecting a baby. But at 12 weeks they did another ultrasound and they told her she was expecting twins.
“It was very obvious that one twin was much larger than the other. There was a three-week difference in size between the two. They couldn’t understand what was happening and why the difference in size was so great,” explained the mother.
She also says that her pregnancy was a roller coaster of emotions and that she could not fully enjoy it due to the concern of the doctors, who were looking for another cause of the difference in size.
But eventually a twin specialist at Bath Royal United Hospital concluded that she had ovulated again.
Little Noah and Rosalie were born in September of last year at 33 + 6 weeks gestation. The boy weighed 1,860 and the girl 1,220 kilos, and both remained admitted to the ICU.
Here we can see the mother with her babies at two months of age. The difference in size between the two is remarkable . Not only because the girl was three weeks younger, but also because her umbilical cord stopped working properly and did not grow much for about a month before they were born.
What is superfetation?
Typically, when conception occurs, the woman’s reproductive system stops producing eggs. Only very rarely can the menstrual cycle repeat itself and a new egg is released while an embryo already exists.
Even rarer is that this ovum is also fertilized: then superfetation occurs, when two embryos of different gestational ages come together . Having been conceived in different cycles, one of them could be born premature. This is a rare case of twins.
In superfetation, the woman becomes pregnant again during pregnancy, resulting in siblings who are born at the same time but having been conceived weeks apart.
In Babies and more | Twins and twins, what is the difference?
