Autoimmune disorders are 5 times more common among women, and incidence tends to peak during reproductive years. Thus, these disorders commonly occur in pregnant women.
Systemic lupus erythematosus:
SLE (see Autoimmune Rheumatic Disorders: Systemic Lupus Erythematosus (SLE)) may first appear during pregnancy; women who have had an unexplained 2nd-trimester stillbirth, a fetus with growth restriction, preterm delivery, or recurrent spontaneous abortions are often later diagnosed with SLE.
The course of preexisting SLE during pregnancy cannot be predicted, but SLE may worsen, particularly immediately postpartum. Complications may include fetal growth restriction, preterm delivery due to preeclampsia, and congenital heart block due to maternal antibodies that cross the placenta. Significant preexisting renal or cardiac complications increase risk of maternal morbidity and mortality. Diffuse nephritis, hypertension, or the presence of circulating antiphospholipid antibodies (usually anticardiolipin antibody or lupus anticoagulant) increases risk of perinatal mortality. Women with antiphospholipid antibodies also have an increased risk of maternal thromboembolic disorders. Neonates may have anemia, thrombocytopenia, or leukopenia; these disorders tend to resolve during the first weeks after birth when maternal antibodies disappear.
Treatment may require prednisone; the lowest possible dose is used. However, 10 to 60 mg po once/day is often needed. Women with antiphospholipid antibodies are also often treated with aspirin (81 mg po once/day) and prophylactic heparin (5,000 to 10,000 units bid sc). For women with severe, refractory SLE, the need to continue immunosuppressants (eg, hydroxychloroquine) during pregnancy is reviewed individually.
RA (see Joint Disorders: Rheumatoid Arthritis (RA)) may begin during pregnancy or, even more often, during the postpartum period. Preexisting RA generally abates temporarily during pregnancy. The fetus is not specifically affected, but delivery may be difficult if the woman's hip joints or lumbar spine is affected. If a woman develops an RA flare during pregnancy, first-line treatment usually begins with prednisone. For refractory cases, other immunosuppressants may be required.
Myasthenia gravis (see Peripheral Nervous System and Motor Unit Disorders: Myasthenia Gravis) varies in its course during pregnancy. Frequent acute myasthenic episodes may require increasing doses of anticholinesterase drugs (eg, neostigmine), which may cause symptoms of cholinergic excess (eg, abdominal pain, diarrhea, vomiting, increasing weakness); atropine may then be required. Sometimes myasthenia becomes refractory to standard therapy and requires corticosteroids or immunosuppressants. During labor, women may need assisted ventilation and are extremely sensitive to drugs that depress respiration (eg, sedatives, opioids, Mg sulfate). Because the IgG responsible for myasthenia crosses the placenta, transient myasthenia occurs in 20% of neonates, even more if mothers have not had a thymectomy.
Immune thrombocytopenic purpura (ITP):
ITP (see Thrombocytopenia and Platelet Dysfunction: Immune Thrombocytopenia (ITP)), mediated by maternal antiplatelet IgG, tends to worsen during pregnancy and increases risk of maternal morbidity. Corticosteroids reduce IgG levels and cause remission in most women, but improvement is sustained in only 50%. Immunosuppressive therapy and plasmapheresis further reduce IgG, increasing platelet counts. Rarely, splenectomy is required for refractory cases; it is best done during the 2nd trimester, when it causes sustained remission in about 80%. IV immune globulin increases platelet count significantly but briefly, so that labor can be induced in women with low platelet counts. Platelet transfusions are indicated only when cesarean delivery is required and maternal platelet counts are < 50,000/μL.
Although antiplatelet IgG can cross the placenta, it only very rarely causes fetal or neonatal thrombocytopenia. Maternal antiplatelet antibody levels (measured by direct or indirect assay) cannot predict fetal involvement. Percutaneous umbilical blood sampling can be diagnostic. If fetal platelet count is < 50,000/μL, intracranial bleeding can occur during labor or vaginal delivery; cesarean delivery is necessary.
Last full review/revision December 2008 by Sean C. Blackwell, MD
Content last modified February 2012