In the past 25 years, we have studied 73 cases of Myasthenia. 19 of these have had 24 pregnancies. We confirm the results that are given in the literature (15). Pregnancy does not trigger off Myasthenia. The action of pregnancy on Myasthenia is variable and there is an equal chance of worsening, improvement or a stationary state of the condition. All the same, patients who are well stabilised and have been for some time do not become worse. Worsening, when it does happen, happens especially in the first trimester of the pregnancy and calls for precise observation of the patient in order to regulate the treatment. Myasthenia has no direct or indirect action on the fetus and the pregnancy is not disturbed. Labour can be normal but the second stage often has to be aided because of the patient's muscle tiredness. In labour and particularly in the second stage an acute crisis can occur with difficulty in breathing. For this it is necessary to have an anaesthetist present who can resuscitate the patient and if necessary give respiratory aid by ventilation. Curare and like substances are absoultely contra-indicated if general anaesthesia is required. Transitory neonatal Myasthenia is rare, but the severity of the respiratory complications can be such that is should be sought for routinely and if there is the slightest doubt the newborn should be transferred to the special care neonatal unit.