We have all heard cases of women who became pregnant while they were already pregnant, probably most of them false. But it could be. Superfetation is the successful fertilization of an egg released during the evolution of pregnancy which results in the conception of twins of different gestational ages.
That is, it is a rare case of twins. It is suggested that this could be due to the continuity of ovulation, despite having started pregnancy. That is, the usual thing is that when conception occurs, the woman's reproductive system stops producing eggs.
Only very rarely can the menstrual cycle be repeated and a new egg is released while an embryo already exists. Even weirder is that this egg is also fertilized: then superfetation occurs, when two embryos of different gestational ages come together.
It is a remarkably more common phenomenon among certain animal species (rodents, horses, sheep ...) than among humans. Most cases in people have been associated with hormonal treatments, ovarian stimulation, hyperstimulation syndrome or assisted fertilization.
Superfetation cases
The first human superfetation report was published by Oskar Föderl in 1932. Since then, several cases have been recorded, a total of 11 confirmed by science.
In 2007, Ame and Lia Herrity were conceived three weeks apart by their parents Amelia Spence and George Herrity in the United Kingdom. In May 2007, Harriet and Thomas Mullineux were also conceived three weeks apart by Charlotte and Matt Mullineux, in Benfleet, Essex (United Kingdom). And the same year we talked about other twin brothers conceived on different dates.
In 2009 we talked about another possible case of superfetation, an American woman who had had a "double pregnancy" of this type.
Superfetation should not be confused with superfecundation, in which two ovules (or more) are fertilized at the same time, something much more common.
We will remain attentive to these rare cases of superfetation, when a woman becomes pregnant again during pregnancy, with brothers who will be born at the same time but having been conceived weeks apart.
