Recurrent miscarriage is frustrating for the physician and a heartbreaking experience for the patient. Approximately 5% of couples trying to conceive have two consecutive miscarriages. Despite a thorough study of patients, the aetiology of this common obstetric complication is unknown in 50% of cases. Known causes include abnormal chromosomes, endocrinological disorders and uterine abnormalities. Although antiphospholipid antibodies have been demonstrated in miscarriages, the role played by alloimmune mechanisms remains unclear. New immunological approaches such as natural killer cells, regulatory T cells, tumour necrosis factor α, cell-derived microparticles, leptin, certain glycoproteins and cytokines should be considered. The management of thyroid diseases and immunological disorders is continuously evolving. Several genetic diagnostic procedures such as parental karyotyping and preimplantation genetic screening should probably not be used routinely. Antiphopholipid syndrome and some recurrent miscarriage-related endocrinological disorders can be effectively treated. Finally, new therapeutic approaches and the pleiotropic effects of old ones have led to improved fetal–maternal outcomes.

Pregnancy is a proinflammatory and hypercoagulable state. Miscarriage concerns approximately 15% of pregnancies. Recurrent miscarriage is a rather rare condition with an estimated incidence of 1% to 3%. However, despite years of investigation, the etiology is not established in up to 50% of cases. A multidisciplinary approach in the evaluation of miscarriage is essential to understand the cause and risk of recurrence. Although genetic factors are the major cause of spontaneous miscarriages, their relationship with recurrent miscarriage is less frequent. Recently, many kinds of genetic polymorphisms have also been found to be associated. Endocrine disorders such as poorly controlled diabetes, polycystic ovary syndrome, and hypothyroidism are linked with recurrent miscarriage. The relationship between recurrent miscarriage and subclinical thyroid disorders and thyroid autoimmunity is disputed, especially in early miscarriages. Uterine malformations should be considered as a cause of recurrent miscarriage. Although autoimmune-based recurrent miscarriage has been described, mainly antiphospholipid antibodies, the role of alloimmune mechanisms remains poorly understood. The influence of congenital thrombophilia is controversial. Antiphospholipid syndrome or antiphospholipid antibody-related recurrent miscarriage, and some endocrinologic disorders, have a specific and effective treatment. Still, the effectiveness of some common treatments needs to be demonstrated.

Objectives: To compare clinical features, laboratory data and fetal-maternal outcomes between 1000 women with obstetric APS (OAPS) and 640 with aPL-related obstetric complications not fulfilling Sydney criteria (non-criteria OAPS, NC-OAPS). Methods: This was a retrospective and prospective multicentre study from the European Registry on Obstetric Antiphospholipid Syndrome. Results: A total of 1650 women with 5251 episodes, 3601 of which were historical and 1650 latest episodes, were included. Altogether, 1000 cases (OAPS group) fulfilled the Sydney classification criteria and 650 (NC-OAPS group) did not. Ten NC-OAPS cases were excluded for presenting thrombosis during follow-up. All cases were classified as category I (triple positivity or double positivity for aPL) or category II (simple positivity). Overall, aPL laboratory categories showed significant differences: 29.20% in OAPS vs 17.96% in NC-OAPS (P < 0.0001) for category I, and 70.8% in OAPS vs 82% in NC-OAPS (P < 0.0001) for category II. Significant differences were observed when current obstetric complications were compared (P < 0.001). However, major differences between groups were not observed in treatment rates, livebirths and thrombotic complications. In the NC-OAPS group, 176/640 (27.5%) did not fulfil Sydney clinical criteria (subgroup A), 175/640 (27.34%) had a low titre and/or non-persistent aPL positivity but did meet the clinical criteria (subgroup B) and 289/640 (45.15%) had a high aPL titre but did not fulfil Sydney clinical criteria (subgroup C). Conclusion: Significant clinical and laboratory differences were found between groups. Fetal-maternal outcomes were similar in both groups when treated. These results suggest that we could improve our clinical practice with better understanding of NC-OAPS patients.

N-terminal pro-brain natriuretic peptide (NT-proBNP) and uric acid are elevated in pregnancies with preeclampsia (PE). Short-term prediction of PE using angiogenic factors has many false-positive results. Our objective was to validate a machine-learning model (MLM) to predict PE in patients with clinical suspicion, and evaluate if the model performed better than the sFlt-1/PlGF ratio alone. A multicentric cohort study of pregnancies with suspected PE between 24⁺⁰ and 36⁺⁶ weeks was used. The MLM included six predictors: gestational age, chronic hypertension, sFlt-1, PlGF, NT-proBNP, and uric acid. A total of 936 serum samples from 597 women were included. The PPV of the MLM for PE following 6 weeks was 83.1% (95% CI 78.5–88.2) compared to 72.8% (95% CI 67.4–78.4) for the sFlt-1/PlGF ratio. The specificity of the model was better; 94.9% vs. 91%, respectively. The AUC was significantly improved compared to the ratio alone [0.941 (95% CI 0.926–0.956) vs. 0.901 (95% CI 0.880–0.921), p < 0.05]. For prediction of preterm PE within 1 week, the AUC of the MLM was 0.954 (95% CI 0.937–0.968); significantly greater than the ratio alone [0.914 (95% CI 0.890–0.934), p < 0.01]. To conclude, an MLM combining the sFlt-1/PlGF ratio, NT-proBNP, and uric acid performs better to predict preterm PE compared to the sFlt-1/PlGF ratio alone, potentially increasing clinical precision.