Too little evidence to show whether continuous oxygen therapy for pregnant women benefits babies in the womb who are smaller than expected.
Babies who receive too little oxygen from their mother's blood can grow more slowly than expected before birth (impaired fetal growth). With extreme lack of oxygen, the baby can die in the womb. Sometimes, it may be suggested that the mother breathe extra oxygen through a face mask 24 hours daily (oxygen therapy) until the baby's birth. The review of trials found that there is too little evidence to show whether the baby's growth improves when women have continuous oxygen therapy from mid-pregnancy until the baby's birth. There is some evidence that fewer babies may die, although further research is needed.