What is Embryonic Breathing?
It is a method of Embracing (i.e. maintaining) Singularity (i.e. simplicity, Wuji center) and keeping it in the neutral state.
An embryo in the womb takes air through the umbilical cord. After two hundred eighty days (of pregnancy), (it) becomes a newborn. Then (the baby) will take the air from the head (Shen Lu). A truthful person (i. e. person who has reached the Dao) breathes deeply but not from the nose. Embryonic Breathing is what Lao Zi said about returning to the baby state (of breathing). This is Embryonic Breathing.