妊娠期重症肌无力

重症肌无力（MG） is twice as common in women than in men, and early-onset myasthenia gravis is shown to affect women of childbearing age. 

How the disease progresses in pregnancy is unpredictable. Estimates suggest that 1 in 20,000 pregnant women has MG (1).

Women with MG should avoid getting pregnant within 2 years after diagnosis. During this period, the risk of maternal death is the highest, and the symptoms are most severe. 

How Does Pregnancy Affect Myasthenia Gravis?

Pregnancy may worsen the symptoms in some women, while it may have no effect or even improve them in others (2). The symptoms are more likely to worsen in the period after childbirth (postpartum). 

However, pregnancy can cause a potentially life-threatening complication called myasthenic crisis (3). Myasthenic crisis is when your respiratory muscles get so weak that you need mechanical ventilation.  

There is no evidence to show that myasthenia gravis affects female fertility. 

Myasthenia Gravis in Pregnancy: What Are the Possible Complications?

If you have myasthenia gravis and get pregnant, the risk of the following complications may be higher:

Preterm labor

Preterm labor (labor beginning before 37 weeks) may occur due to certain medications used to control MG.

Complicated delivery

Though MG does not affect the muscles of the uterus, it may weaken the pelvic floor muscles, which are required to push the baby out. So, you may need forceps or a vacuum device to facilitate delivery. 

Transient neonatal MG (TNMG)

TNMG may occur in 10% to 20% of babies born to women with MG (4). As its name suggests, the condition usually lasts only a few weeks, and 9 in 10 infants recover within two months. 

The symptoms, which begin 12 hours after birth, can include:

• 呼吸困难
• 眼睑下垂
• Poor ability to suck 

Mild to moderate cases can improve with supportive treatment. However, immunoglobulin or plasmapheresis may be necessary in severe cases.

Experts recommend breastfeeding such infants unless you take medicines that can harm the baby. 

Respiratory problems in the mother 

Shallow breathing may occur due to weakened respiratory muscles and elevated diaphragm. Nearly 20% of such cases require mechanical ventilation. 

Treatment of Myasthenia Gravis in Pregnancy

Treatment usually consists of corticosteroids and pyridostigmine (Mestinon). 

Steroids may make you more likely to catch an infection. Therefore, your doctor will closely monitor you for the signs and symptoms of infection. 

Steroid use during pregnancy, especially in the first trimester, has been associated with an increased risk of cleft palate, premature delivery, and gestational diabetes. 

Because of these reasons, your doctor will give you the lowest possible dose of a steroid.  

Pyridostigmine is safe for use during pregnancy and breastfeeding. 

If a myasthenic crisis occurs during pregnancy, you will most likely receive immunoglobulin therapy or plasmapheresis. 

In cases of cesarean delivery, a doctor will use an appropriate anesthetic agent so as not to compromise breathing. 

另请阅读： 重症肌无力 (MG) 患者应避免服用的药物

When to Seek Medical Help

Talk to your doctor if you notice any changes in your symptoms, or if they worsen. Seek immediate medical help if you start having breathing difficulties. 

常见问题解答

How is eclampsia treated in myasthenia gravis patients?

Medications to treat eclampsia in myasthenia gravis patients may include (5):

• Methyldopa (Aldomet)
• Hydralazine (Apresoline)
• Levetiracetam (Keppra)

Use of magnesium sulfate is not recommended, as it can worsen muscle weakness.

Can pregnancy cause a myasthenic crisis?

Pregnancy is a known precipitant of myasthenic crisis. Other causes can be infection,  surgery, pain, emotional stress, and sleep deprivation.  

How is myasthenia gravis treated during pregnancy?

Common medicines used to treat MG during pregnancy are corticosteroids and pyridostigmine (Mestinon). Adequate rest, and a potassium-rich diet are critical to promote recovery.