Can a woman get pregnant during pregnancy? Logic tells us no, since when an egg is fertilized by a sperm, the production process of a new one is interrupted and, consequently, the impossibility of a new natural fertilization. This is the theory, but in practice the human body can give many surprises.
Over time, some cases of what is called superfetation have been documented, which would be the successful fertilization of a new ovum released during the evolution of the pregnancy, a fact that would lead to the conception of twins of different gestational times. This exceptionality can occur between two and four weeks apart.
So what causes a woman to produce a new egg while she is up to a month pregnant? For Dr. Ana Polo, director of Reproductive Medicine at the Puigvert Foundation, “this situation can occur in women with pathologies, such as polycystic ovaries.”
“These patients who have a polycystic ovary, in a few months, for hormonal reasons, can develop two funicles and can ovulate with two ovules.” And for the fertilization of both ovules to be possible, “the ruptures of the funicles would occur asynchronously and would give rise to the possibility of fertilization at two different times.”
As for the gestation of the two babies, fertilized at different times, the pregnancies will not be easy. “When it is time for delivery, the evolution of the two fetuses should be seen, since it would have to occur simultaneously, with a risk of prematurity and the consequences that result for the smallest baby,” explains the doctor.
The medical journal Medindia ensures that superfetation in humans occurs once in every million pregnancies. And to demonstrate its feasibility, the publication includes a case recorded in 2007, when Amelia Spence and George Herrity discovered their superfetation during a regular pregnancy review. The couple and the doctor were puzzled when they saw that “one fetus still looked like a blemish, while the other had four highly visible limbs,” the article says.
Superfetation is more common in other species and not so much among humans. Among the animals most susceptible to experiencing this type of pregnancy, we would find some types of fish, farm animals and rodents.
