The lungs of pregnant women are squashed by the large uterus, especially when they are lying down.

Question: What does this mean?

Answer

The lungs of pregnant women are squashed by the large uterus, especially when they are lying down.

Question: What does this mean?

Answer: This means their lungs don't have as much reserve as non pregnant patients.

Pregnant women also use up oxygen much faster.

Question: What does this mean?

Answer

The lungs of pregnant women are squashed by the large uterus, especially when they are lying down.

Question: What does this mean?

Answer: This means their lungs don't have as much reserve as non pregnant patients.

Pregnant women also use up oxygen much faster.

Question: What does this mean?

Answer: This means that pregnant women drop their oxygen levels much faster at induction.

These factors mean that the patient desaturates very quickly once she stops breathing.

Preoxygenating for 3 minutes gives you a longer time before the oxygen levels start to fall.