Superfetation is a rare phenomenon in which a woman becomes pregnant while already pregnant. This occurs when a woman ovulates and conceives a second time while already carrying a pregnancy. The resulting pregnancies can have different gestational ages, leading to unique challenges in prenatal care and delivery.

One documented case of superfetation occurred in 2009 when an Arkansas woman, Julia Grovenburg, became pregnant with twins conceived two weeks apart. This rare occurrence fascinated the medical community and sparked further research into the science behind superfetation.

Researchers believe that superfetation is possible when a woman continues to ovulate after becoming pregnant due to hormonal imbalances or fertility treatments. While rare in humans, superfetation is more common in certain animal species, such as rabbits and rodents.

Understanding the mechanisms behind superfetation can have implications for fertility treatments and prenatal care. Further research and case studies are needed to fully comprehend this fascinating aspect of conception during pregnancy.