Why does a foetus's lungs don't work properly?
The foetus in embedded in fluid called amniotic fluid. Some
times the foetus takes a breath in that fluid, just before the
delivery. The result is disastrous. If the foetus is born with the
fluid in the lungs, it is going to die in most of the cases. The
foetus is getting all the oxygen and the nutrition from the mother.
This is supplied through the placenta. So the lungs of the foetus
are at rest in the womb of the mother.