Oh, before I go I wanted to share some info I found about breathing techniques during labour. Every bit helps!
Breathing for early labour
Not exactly rocket science: just breathe slowly in and out through each contraction. Try to to keep to a regular rhythm and keep the 'out' breath as long, if not slightly longer, than your 'in' breath.
It can help to count your way through each breath - breathe in for three and out for four - and to breathe in through your nose and out through your mouth.
Breathing for active labour
As each contraction starts give out a long 'sighing' breath and then try to keep to the above slow, regular breathing - in through your nose and out through your mouth
As the contraction builds up you might feel the need to take faster, lighter breaths - just don't overdo it
At the contraction's peak it can help to pant - like a dog - in and out through your mouth, interspersed with a deeper breath every few breaths or so
As the contraction ebbs slow your breathing back down, so that you're back to breathing slowly and regularly by the end of it
Breathing during transition
As you near or reach transition, you may feel a desperate urge to push. Which you desperately need to resist until your midwife gives you the green light. (If you're not fully dilated you can do yourself a great disservice by trying to get your baby out early.)
Your midwife will undoubtedly ask you not to push and probably advise on how best to breathe at this point - but panting and blowing out on your 'out' breath can help hugely... as can getting on all fours and sticking your bum in the air (nobody said labour was glamorous).
To practise this at home - the breathing, not the bum bit - try a 'pant, pant, blow' routine. (Strictly Come Dancing fans might like to think of this as 'quick, quick, slow'.) When you blow out, imagine you're trying to almost, but not quite, blow a candle out.
Breathing during delivery
Unless your midwife tells you otherwise, try not to hold your breath while you're pushing. It's easy to burst a facial blood vessel, which won't look great for those first pictures of you and your baby (in very extreme cases, you can end up with a pneumothorax, aka a hole in your lung).
As each contraction starts, breathe in and out gently, and then, when you feel the urge to push, take a deep breath in, tuck your chin into your chest and breathe or blow out slowly as you bear down.
Try to be led by what your body's telling you to do. Unless you have an epidural, then your body will actually push on its own, regardless of how you're breathing.
Keeping your pelvic floor as relaxed as possible, push from between your legs, rather than holding the tension in your throat, neck or face. (Yes, we know this appears stupidly obvious, but in reality this can be much harder than it sounds.) You'll probably want to push about four times per contraction - so don't forget to take a big breath in before each push.
Some women do small, frequent pushes. They should be spontaneous rather than organised with big breaths - unless you have an epidural and can't feel to push.
As your baby crowns you may be told to stop pushing and just pant - this will help slow things down a bit and can help to prevent you tearing.
Giving birth can be frightening, and when you're scared your breathing rate speeds up and becomes erratic and inefficient at getting oxygen into your lungs. Your baby needs oxygen - and so do you. And if you don't get enough you will feel wobbly and tire quickly, just when you need as much energy as possible. Holding your breath for a long time will have a similar effect.
This is where your birth partner can help by breathing with you during your labour