Myophosphorylase deficiency (McArdle disease) in a patient with normal pregnancy and normal pregnancy outcome.

McArdle disease is a rare, mostly autosomal recessive disorder of deficient myophosphorylation of glycogen in skeletal muscles. Recent knowledge regarding this condition means that women of childbearing age with McArdle disease can expect to labour normally without ill effect. We report a case of a 30-year-old woman in her first pregnancy who had an episode of exercise-induced myoglobinuria with a significant rise in serum creatine kinase (CK) levels in early pregnancy who then laboured normally but did require a caesarean section for a malposition of the fetal head.