Treating the antibodies with the blood-thinning medication heparin and aspirin can help prevent clots. If you have lupus it’s essential that you be tested for antiphospholipid antibodies. You should also be tested for two other antibodies, anti-Ro and anti-La (also known as SS-A and SS-B), that can cross the placenta and are associated with inflammation in the baby’s heart, leading to a condition called heart block which interferes with the electrical impulses that tell the heart to beat. (More on that in the second trimester.)

Second Trimester

If you have anti-Ro or anti-La antibodies, this is the time the effects on the baby become evident. Beginning around your 15th week of pregnancy, your doctor will monitor the fetus by fetal echocardiogram either monthly or weekly, depending on your antibody levels (called titers) and medical history. Echocardiogram is a procedure that uses ultrasound waves to view the action of the heart as it beats. If heart block is detected, your doctor will probably prescribe dexamethasone, a corticosteroid medication that crosses the placenta to help minimize the inflammation. Your doctor will continue to treat and monitor you throughout your pregnancy, because heart block may necessitate early delivery of the baby. If your baby hasn’t developed heart block by week 25, it’s not going to happen, says Michael Lockshin, MD, professor of medicine and Ob/Gyn at Weill Cornell Medical College and director of the Barbara Volcker Center for Women and Rheumatic Disease at the Hospital for Special Surgery in New York.

Late in the second trimester, women with lupus are also at risk of toxemia (also called preeclampsia) – high blood pressure that develops during pregnancy and is accompanied by excessive fluid retention and protein in the urine. While toxemia is a risk late in pregnancy for any woman, women with antiphospholipid antibodies tend to get toxemia earlier.

Recent research has also shown that women with preeclampsia are likely to have a mutation in at least one of three genes associated with a rare disorder called hemolytic uremic syndrome, which triggers a potentially fatal, out-of-control immune response.  This finding suggests that doctors may one day be able to screen women for risk of preeclampsia and that an experimental drug for hemolytic uremic syndrome could potentially be useful in the treatment of preeclampsia.

In the meantime, treatment for preeclampsia is primarily bed rest. The problem doesn’t resolve until the baby is born, so your doctor may have to deliver the baby by Cesarean-section (C-section) as soon as it is mature enough to survive outside the womb, as late as possible and not before the 25th week of pregnancy.

Another problem that can occur with lupus is placental insufficiency, a condition in which blood flow through the placenta isn’t sufficient to supply the necessary nutrients to the baby. The reason may be thickening or blockage of the blood vessels in the placenta and the result may be a low-birth weight baby.

Third Trimester

In the rare event that your baby developed heart block during the second trimester, he or she will likely be scheduled for delivery sometime during this 12-week period, especially if dexamethasone didn’t arrest the condition. Your doctor will continue to monitor the baby closely, and if there are signs that the heart is in trouble, he’ll deliver the baby immediately. “You can’t treat the baby for heart failure inside the mother – at least not yet,” says Dr. Lockshin. In some instances, women with lupus experience premature rupture of membranes. In other words, their water breaks before their baby is due. In those cases, labor may occur spontaneously or the doctor may induce labor or perform a C-section, because once the amniotic fluid leaks there is a risk of infection, says Dr. Petri.

Preeclampsia and placental insufficiency continue to be risks in the third trimester. If you have preeclampsia, you’ll continue to stay on bed rest – possibly in the hospital – for the rest of your pregnancy. Placental insufficiency may lead to premature labor and delivery.  Either of these conditions may necessitate an early delivery.