In recent years it has been recognised that when a woman uses nitrous oxide, other people in the room are exposed to the gas exhaled by her and could therefore be affected by this exposure. There is some research that links prolonged nitrous oxide exposure to a slight increased risk of miscarriage, preterm birth and low birth weight of babies. There is no evidence that it causes abnormalities in unborn babies, although it has been linked to inhibiting folate metabolism, which is a known component in the prevention of abnormalities such as spina bifida. You may wish to read more in Class B about
folic acid during pregnancy.
It is for this reason that the room should be well ventilated and that caregivers or support people who are pregnant should minimise their exposure to the gas. If the midwife caring for you is pregnant and you start to use nitrous oxide, they may opt to ask another midwife take over their care of you, to avoid their exposure.