Foetal means of a foetus — belonging to, or happening in, a baby or young animal before it is born. Doctors talk about a foetal heartbeat, foetal development, and the foetal position: the curled-up shape a baby has in the womb, and that some people still sleep in. It is a medical and science word; you would not use it about a child who has already been born. Though actually, this spelling with oe is British. American English writes fetal. In Taiwan you will meet both; many biology textbooks follow the American spelling. The meaning does not change.

胎兒的（英式拼法；美式作 fetal）