**4. Clinical manifestations of obstetric APS**

Obstetric morbidity of APS is characterized by various pregnancy complications such as recurrent miscarriage, fetal death, and premature birth. These manifestations can occur in the same patient during her childbearing years.

Recurrent early miscarriage (REM) is the most frequent obstetric feature of APS. In the European Registry on Obstetric Antiphospholipid Syndrome REM was observed in almost 54% of women with obstetric APS [67]. On the other hand, aPLs are found in up to 20% of women who experience an early abortion [11]. REM can be caused by various maternal and paternal factors such as anatomical abnormalities, endocrine diseases such as diabetes and thyroiditis, autoimmune diseases, parental chromosomal abnormalities and infectious agents. Therefore, these causes must be systematically excluded specifically in cases where REM is the only clinical manifestation.

In contrast, fetal death and premature birth due to pre-eclampsia and/or placental insufficiency are considered more specific clinical manifestations of APS [3]. Fetal death, in particular the late fetal loss, i.e. beyond 20 weeks of gestation is strongly associated with aPLs [68, 69]. In a population-based study by The Stillbirth Collaborative Research Network in the United States [69], elevated aCL and antiβ2GPI levels were associated with a 3- to 5-fold increased likelihood of stillbirth. Pre-eclampsia, eclampsia, and placental abruption are maternal complications of APS. Preeclampsia occurs in approximately 10–17% of pregnancies with APS, compared to 3–5% of pregnancies without the condition [3, 70]. Preeclampsia in patients with APS is often severe and occurs early in pregnancy [70]. These data were recently confirmed in a case-control study, which found that more than 10% of women who gave birth before 34 weeks' gestation due to pre-eclampsia or

### *Obstetric Antiphospholipid Syndrome DOI: http://dx.doi.org/10.5772/intechopen.101804*

placental insufficiency were positive for aPLs [71]. In a study of 1000 consecutive APS pregnancies, the presence of early pre-eclampsia and early IUGR was found in 181 (18.1%) and 161 (16.1%), respectively, despite treatment [67].

Even when treated with heparin plus low-dose aspirin (LDA), 9–10% of pregnant women with APS develop pre-eclampsia. This highlights the fact that counseling these pregnancies and identifying risk factors are very important to personalize therapy, as will be discussed later.
