Antiphospholipid syndrome: An update on risk factors for pregnancy outcome

The optimal treatment of women with primary antiphospholipid syndrome (APS) is still debated. About 20-30% of women with APS remain unable to give birth to healthy neonates despite conventional treatment, consisting of prophylactic-dose heparin and low-dose aspirin. These cases are defined "refractory obstetric APS". The early identification of risk factors associated with poor pregnancy outcome could be the optimal strategy to establish criteria for additional therapies, such as hydroxychloroquine, steroids, intravenous immunoglobulin, and plasma exchange.

The aim of the present study was to review current literature about risk factors for poor pregnancy outcome.

The PubMed database was used to search for peer-reviewed original and review articles concerning risk factors for pregnancy outcome in APS from 1st January 1990 to 15th January 2018.

History of pregnancy morbidity and/or thrombosis, the association with SLE and/or other autoimmune diseases are well known history-based predictive factors for obstetrical complications, such as miscarriage, maternal venous thromboembolism, intrauterine foetal demise, preeclampsia, and neonatal death. Moreover, laboratory findings associated with poor pregnancy outcome are:triple antiphospholipid antibodies aPL positivity, double aPL positivity, single aPL positivity, false-positive IgM for CMV, and hypocomplementemia. Triple positivity is confirmed as the most significant risk factor by a large body of evidence. Furthermore, the abnormal uterine arteries Doppler velocimetry results are confirmed to be strongly associated with poor pregnancy outcomes in APS. The good performance of the uterine arteries velocimetry, as a negative predictive factor, was reported by different studies. On the contrary, in case of abnormal uterine arteries results, the relevance of a careful surveillance is highlighted for the high risk of maternal-foetal complications. Nevertheless, this tool is a late indicator to suggest any additional treatments.

In order to prevent obstetrical complications and establish the optimal combination therapy, the knowledge at preconception or at the beginning of pregnancy of risk factors associated with poor pregnancy outcome could be a crucial step for management and treatment of APS. In addition, in the preconception assessment a regimen with low-dose aspirin, folic acid, and vitamin D supplementation should be offered, and a treatment strategy has to be established (conventional vs additional therapy). In fact, additional treatment has to be tailored for each patient.