What are the possible complications of myasthenia gravis (MG) in newborns?

Updated: Aug 20, 2019
  • Author: Carmel Armon, MD, MSc, MHS; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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Neonatal MG may result from passive transplacental transfer of antibodies to the nicotinic acetylcholine receptor from the myasthenic mother to the fetus. However, not all infants with detectable levels of antibodies to acetylcholine receptor develop neonatal MG.

The severity of symptoms varies, ranging from mild hypotonia to respiratory distress. Clinical symptoms develop in the first few hours after birth and usually resolve within 2-3 weeks. [66] In the Medical Birth Registry of Norway, 21.3% of children of mothers with MG needed transfer to intensive care units (ICUs), compared with 2% of the reference group. Other studies have shown a neonatal MG incidence of 10-21%, and neonatal disease was reported in 4% (but probably affected 12%) of the Norway registry cohort. [62]

Children of mothers with MG require careful observation in the first few days after birth, and symptoms may respond to anticholinesterase medication. [66] Women with MG should deliver in a facility with a neonatal ICU.

Arthrogryposis multiplex congenita, characterized by multiple joint contractures in utero, occasionally complicates the pregnancy of a mother with MG. Circulating antibodies may inhibit the function of fetal acetylcholine receptors, with little effect on adult acetylcholine receptor function, and may be responsible for this condition. [70]

A high ratio of antifetal to antiadult muscle antiacetylcholine receptor antibodies is predictive of neonatal MG in the first child of a mother with the disease. [71] Elevated alpha-fetoprotein levels may inhibit acetylcholine antibody binding capacity, and this may explain the delay to onset of neonatal MG symptoms after birth. [66]

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