Women with muscle-specific tyrosine kinase (MuSK) antibody-positive myasthenia gravis (MMG) may develop the first symptoms of the disease during pregnancy or within 6 months after giving birth, according to a new study published in Muscle & Nerve. The symptoms of their disease may also worsen during pregnancy. 

“More aggressive medical therapy may be required for pregnant patients with MMG,” the researchers wrote. “Further study is needed to identify the mechanism and risk of worsening of MMG during pregnancy or postpartum.”

To describe the course of MMG, the most common type of MG among women of childbearing age, during pregnancy and within 6 months after birth and assess the effect of the disease on fetal health, a team of researchers led by Janice M. Massey, MD, from the Department of Neurology at Duke University Medical Center in Durham, North Carolina conducted a retrospective study in 10 patients with MMG who became pregnant 14 times between 2003 and 2022.

The researchers reviewed the women’s symptoms before pregnancy, during pregnancy, and 6 months after pregnancy.

Read more about the symptoms of MG

Of the 10 patients that the researchers analyzed, 6 developed symptoms during or after pregnancy. Four women had 2 pregnancies. Of these, 3 developed the disease during their first pregnancy. 

In 62% of patients who already had disease symptoms before becoming pregnant, these increased during and after pregnancy. 

Four patients required rescue therapy with plasma exchange or intravenous immunoglobulins during pregnancy or after giving birth. 

One patient had an emergency C-section due to prolonged labor. 

The researchers reported no other pregnancy complications and said that all infants were healthy at birth.

MG is a rare autoimmune condition affecting the neuromuscular junction. The proteins that typically trigger the autoimmune response are nicotinic acetylcholine receptor (n-AChR), MuSK, and lipoprotein-related protein 4 (LPR4).


Harada Y, Bettin M, Juel VC, et al. Pregnancy in MuSK-positive myasthenia gravis: a single-center case series. Muscle Nerve. Published online May 7, 2023. doi:10.1002/mus.27839