Viagra could be given to women in childbirth to reduce complications and save babies' lives.
A trial is being set up to see if the anti-impotence pill can bring down the number of emergency Caesareans.
The study could lead to a breakthrough that would reduce stillbirths and prevent babies suffering oxygen starvation, which can cause brain damage, epilepsy and other problems.
Women in labour will be given up to three doses of the drug - one every eight hours - in an attempt to boost the supply of oxygen-rich blood to the womb.
Viagra was initially tested as a treatment for angina - chronic pain caused by heart disease. The drug was meant to ease discomfort by dilating blood vessels so more oxygen could reach the heart.
The results were disappointing, but during the research it emerged that it could be used to treat erectile dysfunction.
