When we develop in our mother's womb, the fetus develops inside the placenta.  When we develop on the earth plane, the fetus is the energy body (also called the outerbody or consciousness body) and is outside the 'placenta.'  The physical form itself acts as the placenta, nourishing the developing energy body until it fully matures.

         Fetus with External Placenta             Fetus (energy body) with Internal Placenta

At the time of birth into the vibrational dimension, the essence of the physical mass is absorbed into the flow of the energy body.