Question of the Week

Does a pregnant mother have to breathe more?

Sat, 1st Oct 2011

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Erin Krull asked:

I know that during pregnancy a foetus gets oxygen from its mother via the umbilical cord. I was wondering what effect this has on the mother. Does she inhale more, or simply use oxygen more efficiently? What happens to her oxygen saturation level?



We Posed this question to Dr, Gerald Hackett from The Rosie Maternity Hospital in Cambridge...

Gerald -   Good afternoon.  I'm Gerry Hackett.  I'm a Consultant Obstetrician and Gynaecologist who work at the Rosie.  Amongst many other things, I'm a Foetal Medicine Specialist and you've kindly asked me a A heavily pregnant woman.question about pregnant mums and do they have to breathe more.

Certainly, during pregnancy, a mother and a baby need more oxygen.  Actually, many people think that the oxygen is just for the baby, but actually, at least half the extra oxygen the mother is taking in is for the placenta.  Certainly, also during pregnancy, the mother’s basic metabolism just gets higher.  During pregnancy, mothers do breathe more.  They in fact breathe more deeply.  They don't breathe more often, more frequently, just more deeply.  And actually, strangely enough, despite taking up extra oxygen in her blood, mothers in pregnancy often feel breathless and that's one of the most common symptoms of pregnancy, is breathlessness strangely enough.

So during pregnancy, mothers will feel more breathless that even though they're taking up more oxygen, and letting out more carbon dioxide, they do this in part by movement of the diaphragm.  Of course, as the pregnancy gets larger, you'd expect there to be less movement in the diaphragm.  But in fact, there’s just as much as always and so that tidal volume, the amount of air that a mother will breathe in and breathe out is much the same in pregnancy as outside of pregnancy.  The airflow is much the same.  The extra oxygen passes through the placenta, is taken up by the placenta, but also by the baby and it transfers quickly over to the baby’s side because the haemoglobin – that is the red cells actually in the baby’s circulation- picks up oxygen much more easily than our own haemoglobin would do.  It binds that oxygen and it releases it into the baby’s circulation.

Diana -   Pregnant women don't breathe more often, but they do breathe more deeply.  And surprisingly, the movement their diaphragm can make isn't impeded by the growing baby.  And on the forum, CliffordK said their adding 50 pounds to anybody or make it take more energy to walk across the room and oxygen is required to release that energy. 


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she was breathing heavier while breeding, but not so much during the pregnancy....ithinx CZARCAR, Tue, 27th Sep 2011

The mother oxygenates the blood for both the mother and the baby.  So, the mother's breathing would have to be equivalent to what the baby would ordinarily be moving through its lungs, plus her own breathing.

Carrying the baby might also prevent the mother from taking deep breaths, and thus cause a greater number of shallow breaths.

Adding 50 lbs to anybody will make it take more energy to walk across the room. CliffordK, Wed, 28th Sep 2011

I don't know if there is any truth to this claim, but a friend told me that some women athletes were purposefully getting pregnant and then aborting the fetus for the sake of gaining physical perks that come with getting pregnant such as the change in hormone level and the amount of oxygen uptake. This certainly seems like an ethical dilemma, but I would simply like to know if it is true and if it makes any sense in terms of creating an athletic advantage.  The Penguin, Mon, 17th Oct 2011

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