Sperm cells can live inside a female's body for up to five days, and once ovulation occurs, the egg remains viable for 12–48 hours before it begins to disintegrate.
However, if an ovum is atypically released after the female was already impregnated when previously ovulating, a chance of a second pregnancy occurs, albeit at a different stage of development.
[3] In 2001, a case of spontaneous monopaternal superfecundation was reported after a woman undergoing IVF treatments gave birth to quintuplets after only two embryos were implanted.
Genetic testing supported that the twinning was not a result of the embryos splitting, and that all five boys shared the same father.
[9] In 2015, a judge in New Jersey ruled that a man should only pay child support for one of two twins, as he was only the biological father to one of the children.