Not enough evidence to say if nitric oxide donors or their precursors are helpful in preventing pre-eclampsia and its complications.
Pre-eclampsia is a serious complication of pregnancy occurring in about 10% of women. It is identified by increased blood pressure and protein in the urine, but women often suffer no symptoms initially. It can, through constriction of the blood vessels in the placenta, interfere with food and oxygen passing to the baby, thus inhibiting the baby's growth and causing the baby to be born too soon. Women can be affected by huge swelling and sometimes they go on to have fits. Nitric oxide drugs, like glycerol trinitrate, or their precursors, like L-arginine, may play a role in helping to prevent pre-eclampsia through their action in relaxing blood vessel walls. The review of trials found too few women had been studied, so it was not possible to say if nitric oxide drugs help prevent pre-eclampsia. However, these drugs did cause headaches, often sufficiently severe for women to stop taking the drugs. Future studies need to address these adverse effects and seek women's views.