#1 Getting Pregnant While Pregnant

Truth be told, this is one of those urban legends that everyone thought was completely fictional. But as it turns out, it does happen, albeit rarely. The phenomenon is called superfetation, and it occurs when a successfully fertilized egg gets released during the course of pregnancy. This results in twins, but at a different gestational age.

The second fetus can be born several weeks or months premature, so doctors get very concerned when it happens. And to this day, no one really knows why this can actually happen!