This is truly a Mother's Day gift that Sarah Thistlethwaite will never forget. According to an article from NBC News, in 2014 the new mother she gave birth to what are called Monoamniotic, or "mono mono" twin girls, which means they shared the same amniotic sac and placenta. According to Pregnancy Info, the chances of it happening are between 1 in 35,000 to 1 in 60,000.

We all know that twins are close, but these two were close even before they came into this world. And their closeness was immediately captured on camera when a nurse noticed that one of the newborn sisters reached over and grabbed the hand of the other twin. 

Mono mono twins are a rarity, but there are many possible health risks associated with it. Pregnancy Info says that one of the biggest health risks is the possibility of cord entanglement. "Because the twins have no amniotic membrane separating them, their umbilical cords can easily become entangled." There was a brief worry about the twins, but by the end of the day the new mother and father were holding their babies' hands and doctors were giving a positive prognosis.