[Lewis Thomson (OP)]

Donald has submitted this question to find answers to.

"Hypoxia/hypoxemia is dangerous because metabolically active tissues require the efficiency of aerobic metabolism to function, and work poorly or not at all under anaerobic metabolism. The human brain and heart are highly sensitive to declining oxygen availability, and has been studied. Mountaineers and pilots/air travellers have benefitted from this. Foetuses have much lower oxygen availability, yet developed and grow without injury.  They are born blue, so I suspect they are blue throughout their gestation, and turn pink only after they breath air. So, how do babies survive nine month of hypoxia?"

Can you help him? Leave your thoughts in the comments below...

[alancalverd]

Fetuses don't breathe in utero. All the oxygen required for their functioning comes from maternal blood passed through the placenta and umbilicus, and in most cases the supply is sufficient for normal development. The function of the lungs is to oxygenate blood when the umbilicus is detached.

In the case of a long labor, some babies are born a bit hypoxic but most oxygenate very rapidly once the lungs expand.

It's quite interesting to watch vacuum-packed supermarket meat turn from blue to red when the pack is opened: the reaction is surprisingly rapid considering that there is no circulatory mechanism.

[evan_au]

Babies in utero also have a different form of hemoglobin than the mother; the fetal hemoglobin has a higher affinity for oxygen, which allows it to efficiently extract oxygen from the mother's bloodstream, via the placenta.
See: https://en.wikipedia.org/wiki/Fetal_hemoglobin