Nitrous oxide

Nitrous oxide — an odorless, tasteless gas — is a pain reliever that's inhaled. You give yourself the gas using a hand-held face mask. Nitrous oxide takes effect within a minute.

Pros

Nitrous oxide can be used on and off or continuously during labor. You control the amount you use. You'll be able to walk during labor. If you become too drowsy, you won't be able to hold the mask to your face and you'll stop inhaling the anesthetic.

The effects quickly wear off when you take off the face mask. Nitrous oxide is believed to have little effect on the baby.

Cons

Nitrous oxide doesn't eliminate pain. For relief, it's necessary to breathe in the nitrous oxide about 30 seconds before each contraction. It might cause nausea, vomiting, dizziness and drowsiness.