Myasthenia Gravis and Pregnancy

Myasthenia gravis is a complex disorder where antibodies destroy the connections causing weakness in voluntary muscles. Muscles which appeared to be especially affected are those which control the eyes, mouth, swallowing, throat, and limbs. The degree of muscle weakness will depend upon the severity of the disease. At this time the Myasthenia Gravis Foundation estimates that there are about 20 out of 100,000 men and women who have myasthenia gravis. The incidence appears to be higher in women than it does in men, and higher in women younger than 40.

Women who have myasthenia gravis and choose to become pregnant should know their risk factors both for the pregnancy, the baby and the implications for their disease. While pregnancy is certainly an option, preconceptual counseling is the goal in order to discontinue or reduce corticosteroid medications. Options may be discussed with the expectant mother to decrease the amount of circulating antibodies which crosses the placental barrier to the fetus.

Pregnant women are at higher risk for a myasthenic crisis which is a condition that involves increased weakness in the respiratory system leading to difficulty breathing. In other women the disease may actually go into remission. In either case, pregnancy does not appear to change the progression of the disease. In other words becoming pregnant will not increase the progression of the disease and will not cause a lengthy remission after the pregnancy.

During a pregnancy, women with myasthenia gravis will often have more weakness and fatigue because of the added weight and effort of the pregnancy. Some complications will be more likely including preterm labor and a myasthenic crisis during labor. The theory is that the anti-cholinesterase medications used to treat myasthenia gravis may initiate uterine contractions.

Complications during delivery can include decreased ability to push during the second stage of labor. The uterus itself is not affected by the myasthenia gravis because it is a smooth muscle but the muscles needed for pushing are. This may make forceps or vacuum assisted delivery more likely. In most cases cesarean birth is avoided because of the risk of pulmonary and thromboembolic complications. This means that in some cases women who are pregnant with myasthenia gravis may be at higher risk for a blood clot to the lungs or other area of the body following cesarean section.

Women who have myasthenia gravis should not be medicated with magnesium sulfate, commonly used for treating high blood pressure and preterm labor. This drug blocks the nerve muscle connection and can actually worsen the muscle weakness experienced by individuals with myasthenia gravis.

Current statistics show that between 10 and 25 percent of babies who are born to women with myasthenia gravis may have neonatal myasthenia gravis. This happens when the antibodies cross the placenta to the developing baby. These children will be weak, have poor sucking reflex and may have respiratory difficulties. Thankfully neonatal myasthenia gravis is usually temporary and lasts only a few weeks.

Women with myasthenia gravis who are pregnant need close monitoring with more frequent prenatal visits. It is important that she seek the advice and counsel of an obstetrician and neurologists who is well-versed in the care of women who are pregnant and suffer from myasthenia gravis. Medication adjustments may need to be made during the pregnancy and most physicians will advise patients to avoid emotional and physical stress to decrease the effects of their disease.

Women should be monitored for signs of a myasthenic crisis and ultrasound should be used to assess the blood flow and monitor fetal growth and development. Obstetricians will want to monitor the developing baby for signs of muscle weakness which may indicate fetal myasthenia gravis in order to more appropriately treat the baby at the time of delivery. Other fetal testing may include Doppler flow studies to monitor the blood flow in the uterus and the umbilical cord.

Women who choose to become pregnant and who also suffer from myasthenia gravis can increase their chances for a healthy pregnancy and decrease their chances for any negative impact on their disease by getting early prenatal care and working with their healthcare providers to fully manage their disease.

RESOURCES

Neurology: What is Myasthenia Gravis

Journal of Perinatal and Neonatal Nursing: Myasthenia Gravis and Pregnancy

University of Rochester Medical Center: Myasthenia Gravis and Pregnancy

Myasthenia Gravis Association of Western Pennsylvania: Menstruation and Pregnancy in Women with Myasthenia Gravis

Kuwait Medical Journal: Myasthenia Gravis with Pregnancy