**4.2 Acquired thrombophilias**

APS is indicated in patients with RPL, as well as in patients with adverse gestational outcome or episode of thrombosis without apparent cause [25]. The diagnosis of APS is based on the combination of at least one clinical criterion, which includes thrombotic events and/or gestational morbidity, and a laboratory criterion, which includes three antibodies: lupus anticoagulant, anticardiolipin, and anti-β2 glycoprotein 1 (anti-β2GP1) [25].

In the cases of late gestational loss, lupus anticoagulant was more closely related to RPL than any of the other antibodies [26, 27]. Anticardiolipin (IgG and IgM) has been associated with early and late gestational loss [26, 27]. The relationship between anti-β2GP1 and late gestational loss seems to be controversial [26, 27]. ESHRE recommends for patients with two losses, consecutive or not, to conduct a research for lupus anticoagulant antibodies and anticardiolipin, and the research should consider anti-β2GP1.

The use of combined therapy, low-molecular-weight heparin at prophylactic dose, and low aspirin dose (75–100 mg/day) increases the live birth rate in patients with APS and RPL from 10% to 70–80% [28]. In treatment failure, the use of heparin in therapeutic dose may be used, although there is no benefit evidence [28]. Other treatment regimens with limited evidence are the use of hydroxychloroquine or low dose of prednisolone in the first trimester [28]. The use of immunoglobulin is questioned because studies are limited and show no increase in live birth rate [28].
