Antiphospholipid syndrome and recurrent miscarriage: A systematic review and meta-analysis

Evaluation of Recurrent Pregnancy Loss

Recurrent pregnancy loss (RPL) affects approximately 5% of couples. Although RPL definitions vary across professional societies, an evaluation after a second clinically recognized first-trimester pregnancy loss is recommended. Good quality evidence links parental chromosomal rearrangements, uterine anomalies, and antiphospholipid syndrome (APS) to RPL. In contrast, the relationship between RPL and other endocrine, hematologic, and immunologic disorders or environmental exposures is less clear. Anticoagulant therapy and low-dose aspirin are recommended for patients with RPL who have also been diagnosed with APS. Vaginal progesterone supplementation may be considered in patients experiencing vaginal bleeding during the first trimester. Surgical correction may be considered for patients with RPL in whom a uterine anomaly is identified. Evaluation and management of additional comorbidities should be guided by the patient's history rather than solely based on the diagnosis of RPL, with the goal of improving overall health to reduce complications in the event of pregnancy. Most people with RPL, including those without identifiable risk factors, are expected to achieve a live birth within 5 years from the initial evaluation. Nevertheless, clinicians should be sensitive to the psychological needs of individuals with this condition and provide compassionate and supportive care across all stages.

Effect of anti-thyroid antibodies on recurrent miscarriage: A meta-analysis

SETTING

Previous studies addressed the association between anti-thyroid antibodies and recurrent miscarriage (RM), however, the role of anti-thyroid antibodies in RM patients is debatable.

OBJECTIVES

Therefore, we conducted this meta-analysis and the aim of this current study was to assess whether anti-thyroid peroxidase (anti-TPO) and/or anti-thyroglobulin (anti-TG) antibody positivity was associated with RM.

DESIGN

A meta-analysis was conducted.

PARTICIPANTS

Recurrent miscarriage patients.

METHODS

STATA 12.0 software were applied to compute odds ratios (ORs)/relative risks (RRs) and 95% CIs regarding association between anti-TPO and anti-TG antibodies and the prevalence of RM.

RESULTS

N = 28 studies (8875 participants) explored effect of anti-thyroid antibodies on RM. Analysis of the 28 studies revealed significant association between anti-TPO, anti-TG antibodies and the prevalence of RM with a random effects model (OR/RR = 2.02; 95% CI: 1.63-2.51, p < 0.001; I2 = 44.3%, p value for Q test = 0.004). Analysis of the 20 studies revealed significant association between anti-TPO antibodies and the prevalence of RM with a random effects model (OR/RR = 1.59; 95% CI: 1.25-2.03, p < 0.001; I2 = 43.1%, p value for Q test = 0.022). Analysis of the 14 studies revealed significant association between anti-TG antibodies and the prevalence of RM with a random effects model (OR/RR = 2.25; 95% CI: 1.56-3.23, p < 0.001; I2 = 49.2%, p value for Q test = 0.019).

CONCLUSIONS

Based on the currently available analysis, our findings suggest that women with anti-TPO and/or anti-TG antibodies have a higher risk of RM than that in negative antibody women. Further investigation is needed to better clarify the exact role of the anti-thyroid antibodies in RM and whether treatment is of benefit.

LIMITATIONS

First, differences from various detection methods and reagents used in different studies may affect the diagnostic interpretation of anti-thyroid antibodies, which might influence the accuracy of this meta-analysis. Second, positive anti-thyroid antibodies seem likely to be part of a more general disorder of maternal immune system, due to restrictions of funding and condition, a complete autoantibody screening investigation is hardly to conduct in all participants, and this could be a possible limitation of all included studies. Third, there is no mention of thyroxine therapy on RM, making the meta-analysis even more limited.

How I diagnose and treat antiphospholipid syndrome in pregnancy

ABSTRACT

Antiphospholipid syndrome (APS) is a rare autoimmune disease characterized by arterial, venous, or microvascular thrombosis, pregnancy morbidities, or nonthrombotic manifestations in patients with persistently positive antiphospholipid antibodies. These antibodies bind cellular phospholipids and phospholipid-protein complexes resulting in cellular activation and inflammation that lead to the clinical features of APS. Our evolving understanding of APS has resulted in more specific classification criteria. Patients meeting these criteria should be treated during pregnancy according to current guidelines. Yet, despite treatment, those positive for lupus anticoagulant have at least a 30% likelihood of adverse pregnancy outcomes. Patients with recurrent early miscarriage or fetal death in the absence of preeclampsia or placental insufficiency may not meet current classification criteria for APS. Patients with only low titer anticardiolipin or anti-β(2)-glycoprotein I antibodies or immunoglobulin M isotype antibodies will not meet current classification criteria. In such cases, clinicians should implement management plans that balance potential risks and benefits, some of which involve emotional concerns surrounding the patient's reproductive future. Finally, APS may present in pregnancy or postpartum as a thrombotic microangiopathy, a life-threatening condition that may initially mimic preeclampsia with severe features but requires a very different treatment approach.

Antisense oligonuleotides influences trophoblasts behaviors by changing LncNR_040117 expression in antiphospholipid antibody syndrome-induced recurrent pregnancy loss

OBJECTIVE

The primary objective of this study was to explore whether antisense oligonucleotides (ASOs) that reduce LncNR_040117 expression in patients with antiphospholipid antibody syndrome (APS)-induced recurrent pregnancy loss (RPL), and further decrease apoptosis and improve trophoblasts invasion through mitogen-activated protein kinase (MAPK) pathways. This paper aimed to provide a new strategy to treat APS-induced RPL.

METHODS

In this study, we used quantitative reverse transcription-polymerase chain reaction (RT-qPCR) to analyze the expression level of LncNR 040117 in HTR-8/SVneo cells following transfection with ASOs. Then we utilized Western blotting to test the expression levels of interleukin-1β (IL-1β), intracellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and key molecules of MAPK pathways, including the extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinases (JNK) and p38. In addition, we examined the HTR-8/SVneo cells apoptosis by cell apoptosis assay, and migration and invasion by transwell antibody assay. Each experiment was repeated three times. The data are presented as the means ± SDs, and statistical comparisons were performed using Student's t-test. p < 0.05 was considered significant.

RESULT

Transfected with ASOs, LncNR_040117 was downregulated in trophoblasts compared with APS-induced RPL patients. And LncNR_040117 low expression induced IL-1β and downstream adhesion molecules ICAM-1 and VCAM-1expression level decreased, as well as MAPK pathways downregulation, including the ERK pathway, JNK pathway and p38/MAPK pathway. Furthermore, all these changes resulted in decreased apoptosis and increased migration and invasion of trophoblasts.

CONCLUSION

This study indicated that ASOs that decrease LncNR_040117 expression can reduce apoptosis and enhance the invasion and migration of trophoblasts by regulating the MAPK pathway.

Recurrent Pregnancy Loss Etiology, Risk Factors, Diagnosis, and Management. Fresh Look into a Full Box

Recurrent pregnancy loss is a complex health challenge with no universally accepted definition. Inconsistency in definitions involves not only the number of spontaneous abortions (two or three) that are accepted for recurrent pregnancy loss but the types of pregnancy and gestational age at miscarriage. Due to the heterogeneity of definitions and criteria applied by international guidelines for recurrent pregnancy loss, the true incidence of recurrent miscarriage, which is reported to range from 1% to 5%, is difficult to estimate. Moreover, the exact etiology of recurrent pregnancy loss remains questionable; thus, it is considered a polyetiological and multifactorial condition with many modifiable and non-modifiable factors involved. Even after thoroughly evaluating recurrent pregnancy loss etiology and risk factors, up to 75% of cases remain unexplained. This review aimed to summarize and critically analyze accumulated knowledge on the etiology, risk factors, relevant diagnostic options, and management approach to recurrent pregnancy loss. The relevance of various factors and their proposed roles in recurrent pregnancy loss pathogenesis remains a matter of discussion. The diagnostic approach and the management largely depend on the etiology and risk factors taken into consideration by a healthcare professional as a cause of recurrent miscarriage for a particular woman or couple. Underestimation of social and health consequences of recurrent pregnancy loss leads to compromised reproductive health and psychological well-being of women after miscarriage. Studies on etiology and risk factors for recurrent pregnancy loss, especially idiopathic, should be continued. The existing international guidelines require updates to assist clinical practice.

Antiphospholipid syndrome: advances in diagnosis, pathogenesis, and management

Antiphospholipid syndrome (APS) is a thrombo-inflammatory disease propelled by circulating autoantibodies that recognize cell surface phospholipids and phospholipid binding proteins. The result is an increased risk of thrombotic events, pregnancy morbidity, and various other autoimmune and inflammatory complications. Although antiphospholipid syndrome was first recognized in patients with lupus, the stand alone presentation of antiphospholipid syndrome is at least equally common. Overall, the diagnosis appears to affect at least one in 2000 people. Studies of antiphospholipid syndrome pathogenesis have long focused on logical candidates such as coagulation factors, endothelial cells, and platelets. Recent work has shed light on additional potential therapeutic targets within the innate immune system, including the complement system and neutrophil extracellular traps. Vitamin K antagonists remain the mainstay of treatment for most patients with thrombotic antiphospholipid syndrome and, based on current data, appear superior to the more targeted direct oral anticoagulants. The potential role of immunomodulatory treatments in antiphospholipid syndrome management is receiving increased attention. As for many systemic autoimmune diseases, the most important future direction is to more precisely identify mechanistic drivers of disease heterogeneity in pursuit of unlocking personalized and proactive treatments for patients.

Female reproductive tract microbiome and early miscarriages

Miscarriage is one of the main causes of reproductive loss, which can lead to a number of physical and psychological complications and other long-term consequences. However, the role of vaginal and uterine microbiome in such complications is poorly understood. To review the published data on the function of the female reproductive tract microbiome in the pathogenesis of early miscarriages. The articles published over the past 20 years and deposited in PubMed, Google Academy, Scopus, Elibrary, ResearchGate, and EBSCO databases were analyzed. The review presents new data on the impact of the vaginal and uterine microbiome on the local immunity, including defense against sexually transmitted infections, and its association with other factors of miscarriages. The studies on the microbiome of non-pregnant women with recurrent miscarriages in the anamnesis, patients undergoing IVF, and pregnant women with miscarriages, as well as new directions in the microbiome research are discussed. The majority of studies have demonstrated that the dominant species of the vaginal and uterine microbiome in patients with early miscarriages are non-Lactobacillus bacteria. As many of these bacteria have not previously been detected by cultural studies and their role in obstetric complications is not well defined, further research on the female reproductive tract microbiome, including the microbiome of the cervix uteri, is needed to develop new approaches for the prognosis and prevention of miscarriages.

Inactivation of Yes-Associated Protein Mediates Trophoblast Dysfunction: A New Mechanism of Pregnancy Loss Associated with Anti-Phospholipid Antibodies?

Pregnancy morbidity induced by anti-phospholipid antibodies (aPL+/PM+) is mainly thought to arise from placental abnormalities. We attempted to investigate the effect of aPL on the activity of Yes-associated protein (YAP) in the trophoblast and how YAP regulated human trophoblasts function. Thus, HTR-8 cells were treated with IgG purified from aPL+/PM+ women or normal controls. We found that aPL+/PM+ IgG impacted YAP activity via abrogating YAP expression. Further investigation of the anti-β2GPI-IgG/β2GPI complex showed an inhibition of nuclear YAP level and translocation in a dose-dependent manner, which might be rescued by progesterone in HTR-8 cells. YAP overexpression or knockdown HTR-8 cells were established for the evaluation of cell function and related gene expression in vitro. Loss of YAP arrested cell cycles in the G2/M phase, accelerated cell apoptosis by increasing the ratio of Bax/Bcl2, and disrupted MMP2/9-mediated cell migration and angiogenesis tube formation by VEGF. These findings support a new mechanism of PM associated with aPL through which YAP inactivation induced by aPL perturbs the trophoblast cell cycle, apoptosis, migration, and angiogenesis, finally developing into pregnancy failure.

Long non-coding RNA LINC01347 suppresses trophoblast cell migration, invasion and EMT by regulating miR-101-3p/PTEN/AKT axis

Recurrent miscarriage (RM) is one of the common complications of pregnancy, which is closely related to gene mutation. The profiling of non-coding RNAs showed that the expression level of long non-coding RNA LINC01347 (LINC01347) in the serum of patients with recurrent abortion was significantly increased, which could serve as a potential marker for early diagnosis. However, the biological functions of LINC01347 in the miscarriage remain to be elucidated. In this study, LINC01347 expression levels in HTR-8/SVneo cells and placenta samples were measured by RT-qPCR. The migration ability of HTR-8/SVneo cells was detected by wound-healing assay. Western blotting (WB) assay was conducted to measure E-cadherin, Vimentin, N-cadherin, PTEN, phospho-AKT(S473), phospho-AKT(T308) and AKT levels. Dual luciferase reporter assay and RNA pull-down analysis were performed to validate the molecular interactions. The results showed an upregulation of LINC01347 in the placenta samples of RM patients and HTR-8/SVneo cells. LINC01347 overexpression impaired the invasion and migration of trophoblast cells, while LINC01347 silencing promoted cell migration and invasion. LINC01347 level was also negatively correlated with the changes of epithelial-mesenchymal transition (EMT) markers in trophoblasts. We further demonstrated that miR-101-3p/PTEN/AKT axis played an important role in mediating the biological roles of LINC01347 in the invasion and migration of trophoblasts. In conclusion, our results revealed that LINC01347 suppresses the migratory ability and regulates the EMT processes in trophoblasts by regulating miR-101-3p/PTEN/AKT axis, suggesting that targeting LINC01347 may serve as a strategy to ameliorate RM.

Chinese Herbal Medicines Have Potentially Beneficial Effects on the Perinatal Outcomes of Pregnant Women

Introduction: Tocolytic treatment is beneficial to pregnant women with a risk of premature labor or miscarriage. However, previous reports have shown that progestogen might not be effective and ritodrine may increase the risk of maternal vascular-related diseases. Chinese herbal products (CHP) are used as alternative therapies for pregnant women. The goal was to evaluate the efficacy of combined tocolytic therapy and CHP therapy in pregnancy outcomes for pregnant women in Taiwan.

Materials and Methods: We conducted a retrospective cohort study based on the National Health Insurance Research Database. A total of 47,153 pregnant women treated with tocolytics aged 18–50 years from 2001 to 2015 were selected from two million random samples. According to the medical use of tocolytics and CHP, we divided the users into two groups: western medicine (WM) only (n = 40,961) and WM/CHP (n = 6,192) groups. A propensity score (PS)-matched cohort (6,192 pairs) was established based on baseline confounders. All participants were followed up to perinatal outcomes. Conditional logistic regression analysis was used to examine the effects of CHP use on the odds of miscarriage and preterm birth.

Results: The adjusted odds ratio (OR) for premature birth in the WM/CHP group (n = 411, 6.64%) was significantly lower than in the WM group (n = 471, 7,61%) (0,86, 95% confidence interval [CI], 0.74–0.99). Further subgroup analysis based on the usage of formulae that activate blood and remove stasis or purgative formulae, the adjusted OR of preterm birth of those using these formulae was significantly lower in the WM/CHP group (n = 215, 6.32%) than that in the WM group (n = 265, 7.77%) (OR: 0.79, 95% CI: 0.65–0.96).

Conclusion: We found that the combination of CHP and tocolytics can be beneficial to pregnant women in the prevention of premature birth. Further research is required to investigate causal relationships.

TORCH, Anti-cardiolepin, and Anti-phospholipids in Women with Repeated Miscarriage in Mosul City

  Abstract   Background and Objective: The present study aimed to identify a connection between common viral infections and women who had repeatedly miscarriages. Material and Methods: This study is a retrospective study which has been carried out on 2010 records in Mosul city/Iraq, and the patients were all women of child-bearing age (20-35 years old). All of the women had suffered from an abortion at least once before. The target viruses in charge for this study include; Toxoplasma gundi, Cytomegalovirus, Rubella virus, and Herpes virus. Results and Conclusion: The analysis is based on the detection of the anti-bodies which confirmed a negative correlation between antibodies level and active viral infection, together with no clear association between the presence of active infectious status and miscarriage. Additionally, only few positive cases for each individual patient were positive for viral infection.  Hence, the outcome confirmed no clear association between presence of infectious agent and repeated miscarriage. Nonetheless, rubella and cytomegalovirus have shown the highest contribution in this regard.

Serum antiphospholipid antibody status may not be associated with the pregnancy outcomes of patients undergoing in vitro fertilization

BACKGROUND

Antiphospholipid syndrome (APS) is an autoimmune disease that is associated with recurrent pregnancy loss. It is still controversial whether the presence of antiphospholipid antibodies (aPL) in the serum of patients with in vitro fertilization-embryo transfer (IVF-ET) has a negative effect on the outcomes. In view of the discrepancies, a meta-analysis of the published data was performed to explore the relationship of aPL and IVF-ET outcomes.

METHODS

We searched for all published articles indexed in PubMed, Web of Science, and Cochrane Library, which were retrieved up to April, 2021. A total of 921 studies were yielded, of which 6 finally met the inclusion criteria. We carried out the meta-analysis by pooling results of these studies with Review Manager 5.3 software. The effect index was measured with 95% confidence intervals (CIs) of the relative risks (RRs).

RESULTS

Six eligible studies were included in this meta-analysis, involving 3214 patients. Our results showed that positive aPL was not associated with decreased clinical pregnancy rate (RR 0.97; 95% CI 0.91-1.04). There was no correlation between positive aPL and increased miscarriage risk (RR 1.22; 95% CI 0.94-1.58). Only 5 of the 6 studies referred to live birth rate, but still no association was found between them (RR 0.95; 95% CI 0.81-1.11).

CONCLUSIONS

The results showed that the presence of positive aPL neither decreased clinical pregnancy rate and live birth rate, nor increased miscarriage rate in women undergoing IVF, which is differed from the opinion of clinical practice. More prospective studies with high quality and larger sample size are needed to evaluate the relationship between positive aPL and outcomes of IVF-ET.

Preconception Obstetrics and Rheumatology Consultation: A Protective Factor Against Spontaneous Abortion in Women With Autoimmune Rheumatic Disorders

BACKGROUND

Autoimmune rheumatic disorders are a group of illnesses that significantly affect pregnancy outcomes.

AIM

The aim of this study was to evaluate the incidence and risk factors of spontaneous abortion and its association with maternal medical care in women with autoimmune rheumatic diseases.

METHODS

In this medical record review study, we recruited patients who were referred to our clinic from September 2014 to September 2019. All confirmed pregnancies (based on a positive pregnancy test and sonogram) were included. Binary logistic regression was applied to construct the statistical model.

FINDINGS

The present study involved 97 women (215 total confirmed pregnancies) who were diagnosed with 7 different autoimmune rheumatic disorders. The rate of spontaneous abortion was 28.8%. In the univariate analysis, the preconception obstetrics and rheumatology consultation were negatively associated with spontaneous abortion (p < 0.001; odds ratio [OR], 0.255; 95% confidence interval [CI], 0.136-0.480; and p < 0.001; OR, 0.042; 95% CI, 0.015-0.122, respectively). Perinatal obstetric care had a significant protective effect (p < 0.001; OR, 0.260; 95% CI, 0.139-0.486). The multivariate analysis showed that the preconception rheumatology consultation (p = 0.003; OR, 0.062; 95% CI, 0.010-0.393) was negatively associated with spontaneous abortions. The presence of active diseases before pregnancy (p = 0.005; OR, 9.978; 95% CI, 2.023-49.223), anti-SSA/Ro (p < 0.001; OR, 22.927; 95% CI, 4.921-106.818), and anticardiolipin IgM (p = 0.004; OR, 298.207; 95% CI, 6.209-14,323.037) were associated with a heightened risk of spontaneous abortion.

CONCLUSIONS

A collaborative work carried out by maternal-fetal medicine specialists and rheumatologists could remarkably improve pregnancy outcomes.

Long Noncoding RNA RP11-115N4.1 Promotes Inflammatory Responses by Interacting With HNRNPH3 and Enhancing the Transcription of HSP70 in Unexplained Recurrent Spontaneous Abortion

Background

Unexplained recurrent spontaneous abortion (URSA) is a common pregnancy complication and the etiology is unknown. URSA-associated lncRNAs are expected to be potential biomarkers for diagnosis, and might be related to the disease pathogenesis.

Objective

To investigate differential lncRNAs in peripheral blood of non-pregnant URSA patients and matched healthy control women and to explore the possible mechanism of differential lncRNAs leading to URSA.

Methods

We profiled lncRNAs expression in peripheral blood from 5 non-pregnant URSA patients and 5 matched healthy control women by lncRNA microarray analysis. Functions of URSA-associated lncRNAs were further investigated in vitro.

Results

RP11-115N4.1 was identified as the most differentially expressed lncRNA which was highly upregulated in peripheral blood of non-pregnant URSA patients (P = 3.63E-07, Fold change = 2.96), and this dysregulation was further validated in approximately 26.67% additional patients (4/15). RP11-115N4.1 expression was detected in both lymphocytes and monocytes of human peripheral blood, and in vitro overexpression of RP11-115N4.1 decreased cell proliferation in K562 cells significantly. Furthermore, heat-shock HSP70 genes (HSPA1A and HSPA1B) were found to be significantly upregulated upon RP11-115N4.1 overexpression by transcriptome analysis (HSPA1A (P = 4.39E-08, Fold change = 4.17), HSPA1B (P = 2.26E-06, Fold change = 2.99)). RNA pull down and RNA immunoprecipitation assay (RIP) analysis demonstrated that RP11-115N4.1 bound to HNRNPH3 protein directly, which in turn activate heat-shock proteins (HSP70) analyzed by protein-protein interaction and HNRNPH3 knockdown assays. Most importantly, the high expression of HSP70 was also verified in the serum of URSA patients and the supernatant of K562 cells with RP11-115N4.1 activation, and HSP70 in supernatant can exacerbate inflammatory responses in monocytes by inducing IL-6, IL-1β, and TNF-α and inhibit the migration of trophoblast cells, which might associate with URSA.

Conclusion

Our results demonstrated that the activation of RP11-115N4.1 can significantly increase the protein level of HSP70 via binding to HNRNPH3, which may modulate the immune responses and related to URSA. Moreover, RP11-115N4.1 may be a novel etiological biomarker and a new therapeutic target for URSA.

Hereditary thrombophilia and recurrent pregnancy loss: a systematic review and meta-analysis

STUDY QUESTION

Is there an association between hereditary thrombophilia in pregnant women and risk of recurrent pregnancy loss (RPL)?

SUMMARY ANSWER

Pregnant women with hereditary thrombophilia have an increased risk of RPL, especially for pregnant women with the G1691A mutation of the factor V Leiden (FVL) gene, the G20210A mutation of the prothrombin gene (PGM), and deficiency of protein S (PS).

WHAT IS KNOWN ALREADY

Prior studies have suggested that pregnant women with hereditary thrombophilia have a higher risk of RPL, however, the results are inconsistent; furthermore, a complete overview is missing. This lack of information is an obstacle to the risk assessment of RPL in pregnant women with hereditary thrombophilia. A comprehensive meta-analysis on the relation between hereditary thrombophilia and the risk of RPL is needed.

STUDY DESIGN, SIZE, DURATION

A systematic review and meta-analysis was performed using observational studies published in English before 1 April 2020 to evaluate the relation between hereditary thrombophilia and risk of RPL.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Relevant studies were identified from PubMed, Web of Science, and EMBASE searches and complemented with perusal of bibliographies of retrieved articles. The exposure of interest was hereditary thrombophilia, including FVL mutation, PGM, deficiency of antithrombin (AT), deficiency of protein C (PC), and deficiency of PS. The overall risk estimates were pooled using random effects models. Subgroup and sensitivity analyses were carried out to explore possible sources of heterogeneity and assess the robustness of the results.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 89 studies involving 30 254 individuals were included. Results showed that women with FVL mutation (odds ratio (OR): 2.44, 95% CI: 1.96-3.03), PGM (OR: 2.08, 95% CI: 1.61-2.68), or deficiency of PS (OR: 3.45, 95% CI: 1.15-10.35) had higher risks of developing RPL. Compared with the reference group, there was no observed relation between a deficiency in AT or PC and RPL (all P > 0.05). Heterogeneity in the risk estimates of RPL was partially explained by geographic region, definitions of RPL, types of RPL, and controlled confounders. Sensitivity analyses validated the robustness of the findings.

LIMITATIONS, REASONS FOR CAUTION

Only 39 of the included studies controlled for one or more confounders, and the heterogeneity across all included studies was high. Based on the data available, we cannot determine whether this association is confounded by other potential risk factors of RPL.

WIDER IMPLICATIONS OF THE FINDINGS

This systematic review and meta-analysis show a possible association between hereditary thrombophilia and an increased risk of RPL, suggesting that testing for hereditary thrombophilia should be considered in individuals with RPL.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by the Hunan Provincial Key Research and Development Program (Grant number: 2018SK2062) and National Natural Science Foundation Program (Grant number: 81973137). There are no conflicts of interest.

REGISTRATION NUMBER

N/A.

Anti-Phosphatidylserine/Prothrombin Antibodies in Healthy Women with Unexplained Recurrent Pregnancy Loss

Recurrent pregnancy loss (RPL) affects up to 6% of couples. Although chromosomal aberrations of the embryos are considered the leading cause, 50% of cases remain unexplained. Antiphospholipid Syndrome is a known cause in a few cases. Antiphospholipid antibodies (aPL) anticardiolipin, anti-Beta-2-Glycoprotein-I and Lupus Anticoagulant (criteria aPL) are recommended studies in RPL workup. We tested healthy women with unexplained RPL for criteria aPL and anti-Phosphatidylserine/Prothrombin antibodies (aPS/PT). Patients were classified into three groups according to the number and pregnancy week of RPL: Extra-Criteria (EC), with 2 miscarriages, Early Miscarriage (EM), with ≥3 before pregnancy at week 10 and Fetal Loss (FL), with ≥1 fetal death from pregnancy at week 10. Circulating criteria aPL were absent in 98.1% of EM, 90.9% of FL and 96.6% of EC groups. In contrast, aPS/PT were positive in 15.4% of EM, 15.1% of FL, 16.6% of EC patients and 2.9% in controls. aPS/PT posed a risk for RPL, with an odds ratio of 5.96 (95% confidence interval (CI): 1.85-19.13. p = 0.002) for EM, 7.28 (95% CI: 2.07-25.56. p = 0.002) for FL and 6.56. (95% CI: 1.77-24.29. p = 0.004) for EC. A successful live birth was achieved in all pregnant patients positive for aPS/PT who received treatment with heparin, aspirin and/or hydroxychloroquine.

A novel update on vitamin D in recurrent pregnancy loss (Review)

Recurrent pregnancy loss (RPL) is usually characterized as ≥3 miscarriages before 20 weeks of gestation. Patients with RPL may have autoimmune abnormalities or alloimmune problems. Vitamin D has a major function on the mechanism of immunomodulation at the maternal-fetal interface. However, whether vitamin D can be used as an effective method to treat patients with RPL requires investigation. It has been reported that vitamin D could prevent the occurrence of antiphospholipid syndrome (APS) by reducing the expression levels of anti-β2 glycoprotein and tissue factor in RPL cases with APS. In addition, there is an opposite relationship between vitamin D and thyroid peroxidase antibody levels in autoimmune thyroid disease cases with RPL. Vitamin D changes the ratio of T helper (Th) 1/Th2 and regulatory T cell/Th17 to a certain extent, as well as affects the activity of natural killer cells and the production of cytokines to reduce the incidence of RPL. The objective of the current review was to address the research progress of vitamin D in RPL in recent years, which could facilitate the use of vitamin D treatment to enhance the pregnancy outcome of RPL. Collectively, it was suggested that vitamin D may be used as an important and effective immunotherapeutic agent for patients with RPL.

Predictive value of quad serum markers for adverse pregnancy outcome in antiphospholipid antibody syndrome

PURPOSE

We investigated the validity of quad serum markers for the prediction of adverse pregnancy outcome (APO) in women with antiphospholipid antibody syndrome (APS).

METHODS

We included 75 women with APS delivered at our institution. APO was defined as stillbirth, small for gestational age (SGA), severe preeclampsia, or preterm delivery. First, we compared clinical characteristics between patients with or without composite APO. Second, we compared the rate of APO according to abnormal level of quad serum markers. Lastly, receiver operating characteristic (ROC) curve analysis was performed.

RESULTS

APS mothers with APO showed higher median α-fetoprotein (AFP) and inhibin A compared with those without APO. They were also associated with higher rates of positive risk of Down syndrome and neural tube defect. Elevated AFP, human chorionic gonadotropin (hCG), and inhibin A level was associated with higher rates of stillbirth, SGA, preterm delivery, and composite APO. ROC curve for prediction of stillbirth revealed an area under the curve of 0.835 for AFP, 0.781 for hCG, and 0.932 for inhibin A. For composite APO, the area under the ROC curve was 0.692 for AFP and 0.810 for inhibin A.

CONCLUSION

Elevated AFP, hCG, and inhibin A in women with APS demonstrated a high predictive value for APO, especially stillbirth.

The role of low molecular weight heparin on recurrent pregnancy loss: A systematic review and meta-analysis

To assess the roles of the low molecular weight heparin (LMWH) on recurrent pregnancy loss (RPL). The relevant studies of all randomized controlled trials (RCTs) were retrieved, and the systematic evaluation was conducted. PubMed, Embase, and Cochrane library databases were searched by using keywords, including low-molecular-weight heparin or LMWH, and recurrent miscarriage or recurrent pregnancy loss in pregnant women from their earliest data to February 2020. Two investigators independently evaluated eligibility. Risk ratios (RRs) and their corresponding 95% confidence interval (CI) were determined. To pool the results, this meta-analysis was performed using random-effect model due to the high heterogeneity among these eight studies. A total of eight RCTs involving 1854 participants were included in the meta-analysis involving 963 patients with RPL who were prescribed LMWH (enoxaparin, tinzaparin, or dalteparin) alone and 891 patients who were treated with no LMWH interventions (placebo, folic acid or non-treatment) were compared. Pooled data from the remaining eight RCTs showed the differences between intervention groups and control groups. Compared with control groups, LMWH had significantly improved live births (RR,1.19; 95%CI, 1.03 to 1.38; P = 0.02), and reduced miscarriage rates (RR, 0.62; 95%CI, 0.43 to 0.91; P = 0.01). The study suggested that LMWH could improve the live births and reduce the miscarriage rates of RPL. Therefore, LMWH might be a good treatment choice for women with unexplained PRL.

Using the Immune System to Manage Immunologically-Mediated Pregnancy Loss

Pregnancy is not nearly as successful as laypersons might assume, challenged as it is by several complications such as threatened abortion, spontaneous miscarriage, preeclampsia, and preterm delivery, among others. The maternal immune system has been shown to contribute to the etiopathogenesis of some of these pregnancy complications. Pro-inflammatory and anti-inflammatory cytokines have been studied for their effects on pregnancy because of their powerful and versatile effects on cells and tissues. This review addresses the relationship between pro-inflammatory cytokines and recurrent miscarriage, which is an important complication of pregnancy. References for this review were identified by using PRISMA-IPD (Preferred Reporting Items for a Systematic Review and Meta-analysis of Individual Participant Data) Guidelines by conducting searches for published articles from January 1, 1990 until March 1, 2020 in the following databases: PubMed, Google Scholar, and MEDLINE via OVID by the use of the search terms “recurrent spontaneous miscarriage,” “cytokines,” “progesterone,” “progestogen,” “dydrogesterone,” and “immunomodulation.” This review also presents the proposed mechanisms of action of pro-inflammatory cytokines in pregnancy loss, and then goes on to discuss the modulation of cytokine profiles to a state that is favorable to the success of pregnancy. In addition to its indispensable endocrinologic role of progesterone in pregnancy, it also has some intriguing immunomodulatory capabilities. We then summarize studies that show that progesterone and dydrogesterone, an orally-administered progestogen, suppress the production of pro-inflammatory cytokines and enhance the production of anti-inflammatory cytokines before mentioning clinical studies on progestogen supplementation. These studies support the contention that progestogens should be explored for the immunotherapeutic management of pregnancy complications.

Systematic biological and proteomics strategies to explore the regulation mechanism of Shoutai Wan on recurrent spontaneous Abortion's biological network

ETHNOPHARMACOLOGICAL RELEVANCE

Shoutai Wan (STW) is a classic herbal formula for the treatment of recurrent spontaneous abortion (RSA), and clinical studies have shown the effectiveness of STW on RSA. However, the molecular mechanism of STW treatment of RSA is still unclear.

METHODS

(1) Animal experiments: The normal pregnancy model was established with CBA/J*BALB/C, and the RSA model was established by CBA/J*DBA/2. The RSA model CBA/J*DBA/2 pregnant mice were randomly divided into four groups (RSA model group, STW low, medium and high dose groups) according to the order of pregnancy, respectively. The drug administration starts from the first day of pregnancy to the 14th day of pregnancy. The embryo loss rate (ELR) of each group was calculated. (2) Proteomic analysis of decidual tissue: The total protein of decidual tissue of each group was isolated by solid phase pH gradient 2-DE technique. The differentially expressed protein spots were analyzed and identified by PDQuest images; the peptide quality fingerprinting (PMF) was obtained by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Then, the proteins were identified by Mascot software searching, their functions were identified by bioinformatics strategy. (3) The expression of HSP27, α-enolase and Transferrin was detected by Western blotting and the expression of Annexin A2 and Transferrin was detected by immunohistochemistry. (4) The differential proteins and potential targets were analyzed by systematic biological strategy.

RESULTS

(1) Compared with the normal group, the ELR in the RSA model group was significantly higher (P < 0.01). Compared with the model group, the ELR in the STW high, medium dose groups was lower (P < 0.01). (2) A 2-DE map of the decidual tissue of the RSA model group, normal pregnancy group, STW low, medium and high dose groups was established. Thirty proteins were identified. (3) The results of western blot showed that the expression of HSP27 and a-enolase in the RSA model group was higher than that in the normal group, and the expression of transferrin was lower (P < 0.01). Compared with the model group, the expression of HSP27 and a-enolase in STW high, medium dose groups was decreased (P < 0.01); Compared with the model group, the expression of Transferrin in the STW high dose group was increased (P < 0.01). (5) A lot of RSA treatment-related targets, biological processes and pathways were found after the systematic biological analysis.

CONCLUSION

(1) STW may reduce the ELR of the RSA mice. (2) The results of proteomics suggest that RSA is a complex process involving multiple proteins. STW can regulate the expression of various proteins in the decidual tissue of RSA mice, suggesting that it can act on multiple targets. (3) The results of western blotting of HSP27, a-enolase, transferrin were consistent with the results of proteomic analysis. (4) STW may achieve therapeutic effects by interfering with the targets, biological processes and signaling pathways discovered in this study.

Recurrent miscarriage is not associated with a higher prevalence of inherited and acquired thrombophilia

PROBLEM

Although not being recommended in guidelines, many physicians perform routine screening for thrombophilia in RM patients suspecting a higher prevalence in these patients. The aim of this study was to analyze the prevalence of inherited and acquired thrombophilia in a large cohort of RM patients.

METHOD OF STUDY

Within a multicenter case-control study, n = 820 RM patients and n = 141 controls were included. The prevalence of inherited and acquired thrombophilia including deficiency of protein C/S and antithrombin, elevation of factor VIII activity, APC resistance including mutation in the factor V Leiden gene, mutation in the prothrombin gene and antiphospholipid antibodies were assessed. Further, we performed a meta-analysis of the prevalence of thrombophilia in RM patients including studies between 01/2000 and 01/2020.

RESULTS

An antiphospholipid syndrome (APLS) was only present in RM patients. Increased factor VIII concentration was significantly more prevalent in controls (RM vs controls: 5.8% vs 11.0%). None of the other thrombophilia did differ significantly between RM patients and controls. The meta-analysis revealed no significant difference in the occurrence of these thrombophilia between RM patients and controls.

CONCLUSION

The prevalence of inherited thrombophilia does not differ between RM patients and controls. When analyzing rare events like thrombophilia, a high number of patients are needed to obtain reliable results, which might explain contradictory findings in previous studies analyzing small cohorts of RM patients. Despite being less prevalent than previously described, we still recommend screening for APLS as it is associated with severe pregnancy complications.

The Prevalence and Impact of Polycystic Ovary Syndrome in Recurrent Miscarriage: A Retrospective Cohort Study and Meta-Analysis

Background: The use of different definitions and diagnostic approaches of polycystic ovary syndrome (PCOS) and recurrent miscarriage (RM) has led to a wide range of prevalence rates in the literature. Despite the persistent controversy about the factual prevalence of PCOS in RM, a vast number of studies have revealed evidence about their association with each other. The goals of this study were to evaluate the prevalence of polycystic ovarian morphology and PCOS within the RM population, performing meta-analyses with the obtained data from this study, together with previous reports on this topic and evaluating reproductive outcome in women with RM and PCOS. Methods: A retrospective cohort study with 452 women with RM and a meta-analysis were conducted. The main outcome parameter was the prevalence of PCOS in RM patients. Results: In the retrospective study, the prevalence of PCOS in RM was 9.5%. Negative results for the selected risk factors for RM were present in 283 patients (62.6%). From all evaluated possible underlying causes for RM, only the presence of thrombophilic disorders was significantly associated with PCOS (PCOS: 20.9% versus no PCOS: 7.8%, p = 0.010). In the meta-analysis of three studies on PCOS in RM patients, which used the revised Rotterdam criteria for defining PCOS, an estimated pooled prevalence of 14.3% (95% CI: 6.2–24.9) was found. In the retrospective data set, women in the PCOS group revealed significantly higher luteinizing hormone (LH), testosterone, and Anti-Mullerian hormone (AMH) levels than age- and body mass index (BMI)-matched controls with RM negative for the selected risk facotrs (p < 0.05). The rate of further miscarriages was significantly higher in PCOS women than in controls (71.4% versus 53.6%, respectively; p = 0.031). Conclusions: The prevalence of PCOS seems slightly increased in women with RM. Women with PCOS suffering from RM showed a significantly higher risk for further miscarriage and decreased chances of having a life birth of about 18% which did not reach statistical significance. Therefore, we assume that PCOS plays a moderate role in RM.

Prescription patterns and factors influencing the use of Chinese herbal medicine among pregnant women in Taiwan: a population-based retrospective study

BACKGROUND

The use of Chinese herbal medicine (CHM) has been widely promoted as a natural and safe way to treat illness during pregnancy. However, prescription patterns and factors influencing its use are largely unknown. Therefore, we conducted a population-based study to address these questions.

METHODS

Pregnant women aged 18-50 years were selected from Taiwan's National Health Insurance Research Database between 2001 to 2011. CHM prescriptions and diagnostic records were collected. Demographic data and pre-existing diseases were compared between CHM users and non-users. A multivariate logistic regression analysis was performed to identify possible factors influencing the use of CHM during pregnancy.

RESULTS

A total of 81,873 eligible prescription records were identified, and 16,553 pregnant women were prescribed CHM during pregnancy, yielding a CHM prescription rate of 20.2%. The three most frequently used herbs were Scutellariae Radix (Huang Qin) (4.4%), Eucommiae cortex (Du Zhong) (2.5%), and Atractylodes Rhizome (Bai Zhu) (2.4%). The most frequently used herbal formulae were Dang-Guei-Shao-Yao-San (4.1%), Jia-Wei-Xiao-Yao-San (3.5%), and Xiang-Sha-Liu-Jun-Zi-Tang (2.6%). Multivariate logistic regression revealed that subjects with an older age, a university education, a pre-pregnancy history of CHM use, asthma, chronic renal disease, and cardiac valvular disease and living in a residential area other than northern Taiwan had an increase in adjusted odds ratio for CHM use during pregnancy.

CONCLUSIONS

In this population-based study, we found that demographic factors and pre-existing diseases were associated with the use of CHM among pregnant women. It is worth noting that Leonuri Herba (Yi Mu Cao) and Shao-Fu-Zhu-Yu-Tang should be used with caution in the first trimester. Further research is needed to explore the safety and effectiveness of the use of CHM in pregnant women.

Two of a kind? Immunological and clinical risk factors differ between recurrent implantation failure and recurrent miscarriage

Recurrent miscarriage (RM) and recurrent implantation failure (RIF) are unsolved challenges in reproductive medicine. Whether RIF patients share the same risk factors as RM patients is a matter of debate. Besides clinical factors, immune alterations are discussed in both conditions. The scope of this study was to compare the prevalence of clinical and immunological risk factors in a large cohort of RM and RIF patients. Between 11/2011 and 02/2019, 613 RM and 185 RIF patients were included. A screening for anatomical malformations, endocrine, autoimmune, prothrombotic and parental chromosomal disorders was performed. The immune status was assessed using flow cytometry analysis of peripheral lymphocyte subpopulations and uterine natural killer cells (uNK cells) using immunohistochemistry. RM patients showed a higher rate of intrauterine adhesions and elevated antinuclear antibodies ≥ 1:160 (p < 0.05). A higher prevalence of submucous fibroids and increased factor VIII levels were observed in RIF patients (p < 0.05). The prevalence of an antiphospholipid syndrome (APLS) was low and did not differ between the two groups. RIF patients had higher numbers of peripheral regulatory T-cells (p < 0.05). Significant more RIF patients were diagnosed with elevated uNK cells (p < 0.05). Differences in clinical and immunological risk factors of RM and RIF patients reflect different entities. Lower Tregs in RM and higher uNK cells in RIF patients might be related to the previous exposure of the immune system to fetal cells. The low prevalence of an APLS indicates a potential overestimation of this factor in the pathophysiology of RM and RIF.

Antinuclear antibodies positivity is a risk factor of recurrent pregnancy loss: A meta-analysis

OBJECTIVE

Immunologic mechanisms have been proposed as part of the pathogenesis mechanisms involved in recurrent pregnancy loss (RPL). Presence of positive antinuclear antibodies (ANA) is regarded as a typical feature of autoimmunity. Many studies had tried to clarify the association of ANA with RPL, but the conclusions were controversial. The aim of this meta-analysis was to assess whether ANA was positively associated with increased RPL risk.

METHODS

We searched PubMed and Embase databases for relevant literatures on the association between ANA positivity and RPL. The odds ratios (OR) with 95% confidence intervals (95%CI) were pooled using meta-analysis, and either fixed-effect or random-effect model was used based on heterogeneity across the included studies.

RESULTS

Twenty-one studies with 5038 participants (including 2683 RPL patients and 2355 controls) met the inclusion criteria were included. The total positive rate of ANA was 22.0% (591/2683) in RPL group, and 8.3% (196/2355) in the control group. RPL patients had a significantly higher ANA positive rate than controls (OR = 2.97, 95%CI 1.91-4.64, P<0.00001; I² = 75%), and a significant association between positive ANA and unexplained RPL was also observed (OR = 3.27, 95%CI 2.01-5.31, P<0.00001; I² = 70%). ANA positivity was also significantly associated with increased risk of RPL in women without defined autoimmune diseases (OR = 2.23, 95%CI 1.40-3.55, P=0.0007). Subgroup analysis demonstrated low titers of ANA (1:40≤ANA≤1: 80) were not associated with RPL (OR = 2.44, 95%CI 0.42-14.06, P=0.32), while higher ANA titer (≥1:160) had a significant association with RPL (OR = 45.89, 95%CI 8.44-249.45, P<0.00001). A higher rate of homogenous pattern in RPL patients was observed (OR = 4.89, 95%CI 2.20-10.87, P<0.001), and no significant difference in speckled pattern or nucleolar pattern was found.

CONCLUSIONS

This study demonstrated that ANA positivity was positively associated with increased RPL risk. ANA positivity is an important risk factor for RPL which needed to be screened among women with RPL.

Advances in the Research on Anticardiolipin Antibody

Anticardiolipin antibody (ACA) is a kind of autoantibody and is one of the antiphospholipid antibodies (aPLs). Phospholipids with a negative charge on platelets and endothelial cell membranes are ACA target antigens. ACA is common in systemic lupus erythematosus and other autoimmune diseases and is closely associated with thrombosis, thrombocytopenia, and spontaneous abortion. In 1983, Harris established a method for detecting ACA, and research on the antibody has gained worldwide attention and has developed rapidly. For this review, we browsed articles that cover most of the ACA-related studies in the last 25 years and extracted influential ideas and conclusions in this field.

The pathogenic role of autoantibodies in recurrent pregnancy loss

In the present manuscript, we review the recent research investigating the pathogenic association between most studied autoantibodies and recurrent pregnancy loss. Pregnancy loss represents a common obstetric complication occurring in about 15%-25% of all clinically recognized pregnancies. The recurrence of pregnancy loss identifies a distinct clinical entity, that is recurrent pregnancy loss (RPL), affecting about 2%-4% of couples. Several factors, including age, chromosomal abnormalities, uterine anomalies, thrombophilic disorders, endocrinopathies, hormonal and metabolic disorders, infections, sperm quality, and lifestyle issues, are involved in RPL. The role of autoantibodies in RPL is only partially determined. In some cases (antiphospholipid antibodies [aPL]), their involvement is well established. In other cases (anti-thyroid autoantibodies, antinuclear, anti-transglutaminase, and anti-endomysial antibodies), it is still debated, despite multiple, although not fully conclusive, evidences strongly suggest a possible involvement in RPL. Further extensive research is needed to definitively confirm or exclude their actual role.

Consensus on the investigation of thrombophilia in women and clinical management

Objective

To standardize the investigation and clinical management of women with laboratory and/or clinical abnormalities suggestive of thrombophilia, in order to optimize antithrombotic approach and indication of laboratory tests.

Methodology

A discussion was carried out among 107 physicians (gynecologists/obstetricians, hematologists and vascular surgeons) present at a forum held at the Hospital Israelita Albert Einstein, in São Paulo (SP), Brazil. As a minimum criterion, 80% agreement was established in the voting to each recommendation of conduct in the final document. The cases in which there was agreement below 80% were discussed again, reaching a consensual agreement of conduct for the document writing.

Conclusion

The standardization of an institutional consensus of suggestions of clinical approach contributes to a better management of the group to be evaluated and minimizes risks of intercurrent events. This was the first national consensus on the investigation of thrombophilia in women.

The efficacy of enoxaparin for recurrent abortion: a meta-analysis of randomized controlled studies

Introduction: The efficacy of enoxaparin for recurrent abortion remains controversial. We conduct a systematic review and meta-analysis to explore the influence of enoxaparin versus placebo on recurrent abortion.Methods: We search PubMed, Embase, Web of Science, EBSCO, and Cochrane Library databases through February 2019 for randomized controlled trials (RCTs) assessing the effect of enoxaparin versus placebo on recurrent abortion. This meta-analysis is performed using the fixed or random-effect model when appropriate.Results: Six RCTs involving 1034 patients are included in the meta-analysis. Overall, compared with control group for patients with recurrent abortion, enoxaparin has no obvious impact on live births (RR = 1.06; 95% CI = 0.97-1.16; p = .17), abortion rate (RR = 0.71; 95% CI = 0.45-1.10; p = .13), birth weight (std. MD = 0.38; 95% CI = -0.21-0.96; p = .21), preterm delivery (RR = 0.55; 95% CI = 0.30-1.00; p = .05), preeclampsia (RR = 1.52; 95% CI = 0.42-5.51; p = .52), and postpartum hemorrhage (RR = 1.17; 95% CI = 0.69-1.99; p = .55).Conclusions: Enoxaparin may provide no significant benefits to patients with recurrent abortion.

Macrophage Polarization in Physiological and Pathological Pregnancy

The immunology of pregnancy is complex and poorly defined. During the complex process of pregnancy, macrophages secrete many cytokines/chemokines and play pivotal roles in the maintenance of maternal-fetal tolerance. Here, we summarized the current knowledge of macrophage polarization and the mechanisms involved in physiological or pathological pregnancy processes, including miscarriage, preeclampsia, and preterm birth. Although current evidence provides a compelling argument that macrophages are important in pregnancy, our understanding of the roles and mechanisms of macrophages in pregnancy is still rudimentary. Since macrophages exhibit functional plasticity, they may be ideal targets for therapeutic manipulation during pathological pregnancy. Additional studies are needed to better define the functions and mechanisms of various macrophage subsets in both normal and pathological pregnancy.

Interferons and Proinflammatory Cytokines in Pregnancy and Fetal Development

Successful pregnancy requires carefully-coordinated communications between the mother and fetus. Immune cells and cytokine signaling pathways participate as mediators of these communications to promote healthy pregnancy. At the same time, certain infections or inflammatory conditions in pregnant mothers cause severe disease and have detrimental impacts on the developing fetus. In this review, we examine evidence for the role of maternal and fetal immune responses affecting pregnancy and fetal development, both under homeostasis and following infection. We discuss immune responses that are necessary to promote healthy pregnancy and those that lead to congenital disorders and pregnancy complications, with a particular emphasis on the role of interferons and cytokines. Understanding the contributions of the immune system in pregnancy and fetal development provides important insights into the pathogenesis underlying maternal and fetal diseases and sheds insights on possible targets for therapy.

Vitamin D, autoimmunity and recurrent pregnancy loss: More than an association

Recurrent pregnancy loss (RPL) affects close to 1% of couples; however, the etiology is known in only about 50% of the cases. Recent studies show that autoimmune dysregulation is a probable cause of RPL, which in some cases may be overlooked. In order for a pregnancy to proceed to term, early modulation of immunologic response is required to induce tolerance to the semi-allogenic fetus. Certain subsets of both the innate and adaptive immune responses play a role in the induction of fetomaternal tolerance. A relatively predominant T-cell helper (Th) 2 and T regulatory (Treg) cell population seem to favor a better pregnancy outcome, whereas Th1 and Th17 cell populations appear to have an opposite effect. Lately, the role of vitamin D in the modulation of immune response was established. Vitamin D has been shown to promote a more favorable environment for pregnancy through various mechanisms, such as enhancement of the shift toward Th2 cells and regulation of immune cell differentiation and cytokine secretion. Therefore, it seems that vitamin D deficiency sways the balance toward a worse outcome and may play a part in recurrent pregnancy loss. This review sheds light on the immunologic changes, which occur in early pregnancy and the regulatory role vitamin D has in the maintenance of this delicate balance.