Myasthenia gravis: consequences for pregnancy, delivery, and the newborn.

OBJECTIVE: To investigate the effect of maternal myasthenia gravis (MG) on giving birth and on the newborn.

METHODS: A retrospective cohort study for 1967 through 2000 was undertaken, using data from the Medical Birth Registry of Norway, based on the compulsory notification of all births. The target group consisted of 127 births by mothers with MG. The reference group consisted of all 1.9 million births by mothers without MG.

RESULTS: Women with MG had a higher rate of complications at delivery (40.9% vs 32.9%, p = 0.05), and in particular the risk of preterm rupture of amniotic membranes was three times higher in the MG group compared to the reference group (5.5% vs 1.7%, p = 0.001). The rate of interventions during birth was raised (33.9% vs 20.0%, p < 0.001) and cesarean sections doubled (17.3% vs 8.6%, p = 0.001). Five children (3.9%) born by MG mothers had severe anomalies, and three of them died.

CONCLUSIONS: MG is associated with an increased risk for complications during delivery. This is linked to a higher occurrence of interventions during birth.