Failing maternal-fetal tolerance in SLE (FaMaLE): a prospective cohort study for finding the molecular mechanisms behind pregnancy complications.

Introduction: Pregnant women with SLE have an increased risk of maternal complications and adverse fetal outcomes. These include pre-eclampsia, preterm birth and fetal growth restriction. Interestingly, this increased risk persists in subsequent pregnancies, whereas it decreases in healthy women due to the development of maternal-fetal tolerance. As maternal-fetal tolerance is crucial for a healthy pregnancy, we hypothesise that its failure contributes to the increased risk of pregnancy complications in women with SLE. Therefore, we initiated the failing maternal-fetal tolerance in SLE (FaMaLE) study to investigate the failure of maternal-fetal tolerance in pregnant women with SLE.

Methods and analysis: In the FaMaLE study, women with SLE and healthy women are included in their first trimester of pregnancy (<14 weeks gestational age) at Amsterdam UMC. Throughout the pregnancy, data on SLE disease activity, pregnancy course and medication use are collected. Peripheral blood is collected once per trimester, within 48 hours before delivery and 5-12 weeks post partum. In addition, the placenta is collected after delivery. Whole blood, peripheral blood mononuclear cells and placenta samples are freshly analysed by flow cytometry to assess immune cell composition. The resulting data are analysed in relation to SLE disease course, pregnancy course and pregnancy outcomes.

Ethics and dissemination: The study has been approved by the Amsterdam UMC Medical Ethics Committee and all participating women will be asked to provide informed consent. The findings will be disseminated through peer-reviewed publications, presentations at scientific meetings and via patient organisations.