**4. SLE & other autoimmune diseases**

## **4.1 Presence of antiphospholipid antibodies**

The presence of antiphospholipid antibodies (aPL) during pregnancy is associated with significant risk of maternal and fetal adverse events. The prevalence of aPL in SLE is about 12–44% for anticardiolipin (aCL), 15–34% for lupus anticoagulant (LAC) and 10–19% for anti-beta2 glycoprotein I (β2GPI) antibodies [25]. These antibodies are responsible for an autoimmune hypercoagulable state, known as antiphospholipid syndrome (APS). Even though aPL are present in about a half of patients with SLE, only a fraction of these patients develops antiphospholipid syndrome (APS), which manifests as thrombotic and/or obstetric adverse events, mediated by persistent circulating aPL detected by means of three tests: LAC, aCL and β2GPI antibodies, repeated twice with an interval of 12 weeks apart. A different subset of patients, the so-called "aPL carriers", has been described. These are aPL positive individuals without clinical manifestations, that are at high-risk of prematurity, pre-eclampsia, eclampsia, or HELLP (hemolysis, elevated liver enzyme levels, low platelet count) syndrome. The most severe form of APS is catastrophic antiphospholipid syndrome (CAPS) a potentially fatal and rare condition that women may develop during pregnancy. Its diagnosis is challenging and aggressive treatment is crucial in order to save a patient's life [23].

The outcomes of pregnancies in patients with aPL have significantly improved and live birth rates over 80% are achieved nowadays. The management is based on the risk of profile of aPL and/or previous thrombotic and/or obstetric complications.

#### **4.2 Presence of anti-Ro antibodies**

Anti-Ro/SSA and/or anti-La/SSB autoantibodies are detected in approximately 40% of patients with SLE. The transplacental passage of maternal IgG antibodies (anti-Ro/SSA and anti-La/SSB) may lead to neonatal lupus in 1–2% of all pregnancies affected by SLE [26].

Congenital Heart Block (CHB) is the most severe manifestation, affecting 2% of pregnancies with positive antibodies (especially anti-Ro/SSA) and without a previous history of complicated pregnancies. This usually manifests between the 18th and 24th weeks of gestation. The risk increases significantly 10 to 15% in patients who have a prior history of another neonate affected with cutaneous lupus and up to 15–20% in those with a prior neonate affected with CHB [27].
