Buy the Book PDA Download

Update Me E-mail alerts The Merck Manual Minute

Print This Topic Email This Topic

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 increases risk of perinatal mortality. Women with anticardiolipin antibody (lupus anticoagulant), present in about 5 to 15% of women with SLE, have an increased risk of abortion, stillbirth, and maternal thromboembolic disorders.

Treatment may require prednisone Some Trade Names
DELTASONE
Click for Drug Monograph
; the lowest possible dose is used. However, 10 to 60 mg po once/day is often needed. Some patients are also treated with aspirin Some Trade Names
BUFFERIN
ECOTRIN
GENACOTE
Click for Drug Monograph
(81 mg po once/day) and prophylactic heparin Some Trade Names
HEPFLUSH-10
Click for Drug Monograph
(5,000 to 10,000 units bid sc). If the woman has severe, refractory SLE, the need to continue immunosuppressants (eg, hydroxychloroquine Some Trade Names
PLAQUENIL
Click for Drug Monograph
) during pregnancy is reviewed individually.

Rheumatoid arthritis (RA): RA (see Joint Disorders: Rheumatoid Arthritis (RA)) may begin during pregnancy or, even more often, the postpartum period. Preexisting RA generally abates during pregnancy. The fetus is not specifically affected, but delivery may be difficult if the woman's hip joints or lumbar spine is affected.

Myasthenia gravis: (see Peripheral Nervous System and Motor Unit Disorders: Myasthenia Gravis) The course varies during pregnancy. Frequent acute myasthenic episodes may require increasing doses of anticholinesterase drugs (eg, neostigmine Some Trade Names
PROSTIGMIN
Click for Drug Monograph
), which may produce symptoms of cholinergic excess (eg, abdominal pain, diarrhea, vomiting, increasing weakness); atropine Some Trade Names
ATROPEN
ATROPINE-CARE
SAL-TROPINE
Click for Drug Monograph
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). 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: Idiopathic Thrombocytopenic Purpura (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 platelets significantly but briefly, so that labor can be induced in women with low platelet counts. Platelet transfusions are indicated only when cesarean section is required and maternal platelet counts are < 50,000/μL.

Although IgG can cross the placenta, causing fetal and neonatal thrombocytopenia, it rarely occurs. Maternal antiplatelet antibody levels (measured by direct or indirect assay) cannot predict fetal involvement, and the fetus may be involved even when mothers have been treated with corticosteroids or previous splenectomy and do not have thrombocytopenia. Percutaneous umbilical blood sampling can be diagnostic. If fetal platelet count is < 50,000/μL, intracranial bleeding can occur during labor or delivery, and delivery by cesarean section is necessary.

Last full review/revision November 2005

Content last modified November 2005