Superfetation

Superfetation, over- fertilization (Latin: Superfetatio ), or Doppelträchtigkeit refers to a phenomenon that occurs in the reproduction of different species (eg, hare, cat and Zwergkärpfling ). In females, the hare occur in exceptional cases to double pregnancy, that is, an already pregnant doe can, even before it has set, be fertilized again. In cats, there is a 10% probability that they will " überbefruchtet ". In viviparous Zwergkärpfling contrast superfetation is the normal case. This allows the females of this species according to age and body size within a " throw -cycle " of about 4 weeks accommodate up to 30 babies at almost as many as the much larger ( adult ) females of related species such as Metallkärpfling, Guppy or platy on a roll.

In humans, the superfetation usually is unlikely because here the hormone levels after ovulation within 24 hours or so changes in the body that no further ovulation is possible. A second ovulation is only possible shortly after the first, which can then lead to fraternal twins. However, since no pregnancy in this case ( but only a fertilized egg on its way to the uterus ), this is not superfetation, but a Superfecundatio.

Nevertheless, in 2008 and 2009 at two women Superfötationen were noted over the years. Within one cycle, two eggs were fertilized independently, thus developed two different old fetuses. The planned birth dates were December 24 and 10 January, but both babies came on the same day (December 2 ) to the world.