At 12 weeks gestation, unborn babies are rapidly growing. Not only do they have beating hearts, but hands and feet, fingers and toes, tongues and palates, and hair follicles forming on their heads. Babies at this stage can do somersaults, forward rolls, stretches— and as this baby shows, jumps.
The baby now sleeps, awakens and exercises its muscles energetically – turning its head, curling its toes, and opening and closing its mouth. The palm, when stroked, will make a tight fist. The baby breathes amniotic fluid to help develop its respiratory system.
Here’s an amazing ultrasound showing an unborn baby at 12 weeks jumping in his mother’s womb: