Anti-phospholipid antibodies and other immunological causes of recurrent foetal loss--a review of literature of various therapeutic protocols

Progress in the field of animal models of antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by recurrent arteriovenous thrombosis and pathological pregnancy, accompanied by persistent antiphospholipid antibodies, (aPL). The incidence of APS is increasing year by year, clinicians lack of understanding of this type of disease, easy to misdiagnose and miss the diagnosis. Therefore, it is extremely important to establish a suitable animal model to reduce the process of disease development as much as possible and improve clinicians' understanding and understanding. This review will summarize the animal models of APS from the aspects of modeling methods, modeling mechanism, evaluation indicators and advantages and disadvantages of methods, providing a reference for finding an animal model highly similar to human APS, helping researchers to further clarify the pathogenesis of APS and find potential therapeutic targets, so as to achieve early diagnosis, early intervention, and ultimately improve the prognosis of patients.

Glucocorticoids Improve the Pregnancy Rate and Outcome in Women With Unexplained Positive Autoantibodies: A Systematic Review and Meta-Analysis

The effect of glucocorticoid therapy on women with unexplained positive autoantibodies is under debate. This systemic review and meta-analysis were performed to evaluate whether glucocorticoid administration can improve the pregnancy outcome of this population. Relevant publications were searched from databases, and a total of seven prospective and retrospective cohort studies that investigated the effects of glucocorticoid administration on women with unexplained positive autoantibodies, were included. The outcomes of our systematic review and meta-analysis were measured in terms of risk ratios (RR) with 95% confidence intervals (CI) using fixed or random effect models. We found that glucocorticoid treatment improved the clinical pregnancy rate (RR 2.19, 95% CI 1.64–2.92) and live birth rate (RR 1.92, 95% CI 1.17–3.16), especially when glucocorticoid administration was started before pregnancy (clinical pregnancy rate: RR 2.30, 95% CI 1.58–3.34; live birth rate: RR 2.30, 95% CI 1.58–3.34). However, no effect of glucocorticoids on the miscarriage rate was found (RR 0.75, 95% CI 0.55–1.02) regardless of the time of drug administration. Our systematic review and meta-analysis support the rational use of glucocorticoids in women with unexplained positive autoantibodies.

Infertility, Miscarriage, Stillbirth, and the Risk of Stroke Among Women: A Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

Stroke is one of the leading causes of mortality, and women are impacted more from stroke than men in terms of their absolute number and in having worse outcomes. A growing number of studies have explored the association between pregnancy complications, pregnancy outcomes, and stroke. Limited studies, however, have investigated links involving infertility, miscarriage, and stillbirth, which could plausibly be associated via a background of endocrine conditions, endothelial dysfunction, and chronic systematic inflammation. This review aims to summarize current evidence and provide up-to-date information on the associations of infertility, miscarriage, and stillbirth, with stroke incidence.

METHODS

A comprehensive literature search was conducted for cohort and case-control studies on associations between infertility, miscarriage, stillbirth, and stroke up to September 26, 2020. Seven databases were searched: PubMed, Embase, Cochrane, CINIHL, PsyclNFO, Wanfang, and CNKI. Random-effects models were used to estimate the pooled hazard ratios (HRs) and 95% CIs.

RESULTS

Sixteen cohort studies and 2 case-control studies enrolling 7 808 521 women were included in this meta-analysis. Women who had experienced miscarriage or stillbirth were at higher risk of stroke (miscarriage: HR, 1.07 [95% CI, 1.00-1.14]; stillbirth: HR, 1.38 [95% CI, 1.11-1.71]) than other women. The HRs of stroke for each additional miscarriage and stillbirth were 1.13 (95% CI, 0.96-1.33) and 1.25 (95% CI, 1.06-1.49), respectively. In subgroup analysis, increased risk of stroke was associated with repeated miscarriages and stillbirths (miscarriage ≥3: HR, 1.42 [95% CI, 1.05-1.90]; stillbirth ≥2: HR, 1.14 [95% CI, 1.04-1.26]). Associations between infertility and stroke were inconsistent and inconclusive (HR, 1.07 [95% CI, 0.87-1.32]).

CONCLUSIONS

Miscarriage and stillbirth are associated with increased risk of stroke among women, which could be used as a contributing risk factor to help identify women at higher risk of stroke.

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.

IL-10 to TNFα ratios throughout early first trimester can discriminate healthy pregnancies from pregnancy losses

PROBLEM

Embryo implantation and placentation require a careful immunological balance. Cytokines such as IL-10 and TNFα have been implicated as markers of dysregulation, but have only been studied at a single time point or after a pregnancy loss. Our objective was to determine normative patterns of serum levels of IL-10 and TNFα and their ratio throughout the first trimester in healthy pregnancies and to determine if this pattern differs from pregnancy loss.

METHOD OF STUDY

Two prospective longitudinal cohorts of gravidae including in vitro fertilization (IVF) and naturally conceived pregnancies with serial blood draws. Cytokines were assayed using Simple Plex. In the IVF cohort, we monitored from the implantation day up to 6 weeks of gestation; whereas in the naturally conceived cohort, sample collection began at 4 weeks and throughout the whole first trimester.

RESULTS

IL-10 concentrations in normal pregnancies were significantly higher than in pregnancies ending in a loss starting at 6-8 weeks of gestation, while TNFα concentrations were significantly lower in normal than in pregnancies ending in a loss starting at 3-5 of gestation weeks. The IL-10 to TNFα ratio in normal pregnancies was significantly higher from 4 to 9 weeks compared to pregnancies that were lost (t test, P < .05). Changes were observed before any symptoms of miscarriage were present.

CONCLUSION

We provide evidences of differences in early immunomodulation in healthy pregnancies vs those destined to end in first-trimester loss. The ratio of IL-10 to TNFα rises significantly higher in viable pregnancies as early as 4.5 weeks compared to pregnancies loss.

Immune modulation of i.v. immunoglobulin in women with reproductive failure

Background

The mechanism of maternal immune tolerance of the semi‐allogenic fetus has been explored extensively. The immune reaction to defend from invasion by pathogenic microorganisms should be maintained during pregnancy. An imbalance between the immune tolerance to the fetus and immune activation to the pathogenic organisms is associated with poor pregnancy outcomes. This emphasizes that the immune mechanism of successful reproduction is not just immune suppression, but adequate immune modulation.

Methods

In this review, the action of i.v. immunoglobulin G (IVIg) on the immune system and its efficacy in reproductive failure (RF) was summarized. Also suggested is the indication of IVIg therapy for women with RF.

Main findings (Results)

Based on the mechanism of the immune regulation of IVIg and following confirmation of the immune modulation effects of it in various aberrant immune parameters in patients with RF, it is obvious that IVIg is effective in recurrent pregnancy losses and repeated implantation failures with immunologic disturbances.

Conclusion

The authors recommend IVIg therapy in patients with RF with aberrant cellular immunologic parameters, including a high natural killer cell proportion and its cytotoxicity or elevated T helper 1 to T helper 2 ratio, based on each clinic's cut‐off values. Further clinical studies about the safety of IVIg in the fetus and its efficacy in other immunologic abnormalities of RF are needed.

Pregnancy outcomes of antiphospholipid syndrome: In a low resource South Asian setting

PROBLEM

Antiphospholipid syndrome is associated with recurrent pregnancy loss, and specific treatment improves pregnancy outcome. Laboratory diagnosis is limited in South Asia. We assessed management outcomes of definite/probable antiphospholipid syndrome treated at a tertiary centre in Sri Lanka.

METHOD

Descriptive cross-sectional study of pregnancy outcomes with heparin and aspirin therapy.

OUTCOME MEASURES

miscarriage, intrauterine death and live birth when compared to previous untreated pregnancies.

RESULTS

Of 646 gestations in 145 women, 146 (22.6%) received specific treatment. In the preceding pregnancies without specific treatment, the rates of miscarriage, late fetal loss, stillbirth and live birth were 60%, 26%, 8% and 7%, respectively. Following specific treatment with low-dose aspirin ± low-molecular weight heparin in 146 pregnancies (145 women), the rates of miscarriage, late fetal loss, stillbirth and live birth were 14%, 10%, 3% and 74%, respectively. Mean birth weight was 2.54 ± 0.62 kg, preterm births complicated 32 (29.6%) with a mean gestational age at delivery 33.7 ± 2.6 weeks, with three neonatal deaths. Maternal complications were: pre-eclampsia 16 (10.9%), gestational diabetes 28 (19.2%), antepartum haemorrhage in 1 patient. Only 73/145 (50.3%) women had laboratory confirmation of antiphospholipid syndrome, while others were treated empirically. Live births in diagnosed vs. empiric treatment - 80.8% vs. 67.1%.

CONCLUSION

Pregnant women with clinical antiphospholipid syndrome when treated with low-dose aspirin and heparin, the live birth rate of 7% in the previous pregnancy resulted in live births of 74% in a resource limited South Asian setting.

Exposure to ambient air pollutants and spontaneous abortion

AIM

This study aimed to evaluate the correlation between ambient concentrations of air pollutants and first-trimester spontaneous abortion.

MATERIAL AND METHODS

This was a retrospective case–control study, which was conducted on 296 women from June 2010 to February 2011 in Tehran, Iran. Cases were 148 women who experienced a spontaneous abortion before 14 weeks of gestation while the controls were 148 pregnant women after 14 weeks of gestation and groups were matched on sociodemographics and obstetrics characteristics. The samples were recruited randomly from 10 hospitals. In total, pollutants concentrations were collected at 29 stations hourly throughout the study area. We estimated the mean exposure for each participant and investigated the association between spontaneous abortion and ambient pollutants.

RESULTS

Findings demonstrated that the average of ambient air pollutants in the cases was significantly higher than in the controls (P < 0.05). The odd ratios of abortion in the areas with higher concentrations of CO, NO₂, O₃ and PM₁₀ were 1.98, 0.96, 0.94 and 1.01, respectively (P < 0.05). Also, the model showed that there was no significant association between prenatal exposures to SO₂ and abortion (P > 0.05).

CONCLUSIONS

Our findings suggest that pregnant women exposed to ambient air pollutants may be at increased risk of spontaneous abortion. Confirmation by further research is needed.

Microchimerism in women with recurrent miscarriage

Miscarriage is the most common pregnancy complication, and recurrent miscarriage (3 or more consecutive pregnancy losses) affects 1-5% of couples. Maternal-fetal exchange and the persistence of exchanged material as microchimerism appears to be disrupted in complicated pregnancies. We recently conducted a longitudinal cohort study of microchimerism in women with recurrent miscarriage. Our initial data raise multiple questions that require further investigation. Here, we review our data from this recent study and provide additional information regarding microchimerism in the granulocyte cell layer. This area of investigation offers a unique window into early reproductive events, and future related studies have the potential to identify novel therapeutic approaches and insights into human evolution.

Microchimerism in recurrent miscarriage

Maternal-fetal cell exchange during pregnancy results in acquisition of microchimerism, which can durably persist in both recipients. Naturally acquired microchimerism may impact maternal-fetal interaction in pregnancy. We conducted studies to ask whether microchimerism that a woman acquired from her own mother is detectable before or during pregnancy in women with recurrent miscarriage. Fetal microchimerism was also assayed. Women with primary idiopathic recurrent miscarriage (n=23) and controls (n=31) were studied. Genotyping was conducted for probands, their mothers and the fetus, a non-shared polymorphism identified and quantitative polymerase chain reaction performed to measure microchimerismin peripheral blood mononuclear cells. Preconception comparisons were made between recurrent miscarriage subjects and controls, using logistic regression and Wilcoxon rank sum. Longitudinal microchimerism in subsequent pregnancies of recurrent miscarriage subjects was described. There was a trend toward lower preconception detection of microchimerism in recurrent miscarriage versus controls, 6% vs. 19% (1/16 vs. 6/31, P=0.2). During pregnancy, 3/11 (27%) of recurrent miscarriage subjects who went on to have a birth had detection of microchimerism from their own mother, whereas neither of two subjects who went on to miscarry had detection (0/2). This initial data suggest that microchimerism from a woman's own mother, while detectable in women with recurrent miscarriage, may differ from controls and according to subsequent pregnancy outcome. Further studies are needed to determine the cell types, quantities and any potential functional role of microchimerism in recurrent miscarriage.

Recurrent spontaneous abortions, Hashimoto thyroiditis and alopecia totalis: response to anticoagulation and intravenous immunoglobulin therapy

INTRODUCTION

Although numerous studies indicated a link between antithyroid antibodies and recurrent spontaneous abortions (RSA), consensus on the treatment of this condition is still lacking.

CASE REPORT

We present a case of a 35-year-old pregnant woman (gestation week 4) with primary hypothyroidism, total alopecia, high level of positive antithyroid antibodies, and history of two recurrent spontaneous abortions in early pregnancy. Along with L-thyroxin substitution, intravenous human immunoglobulin (IVIg) combined with anticoagulation and antiaggregation therapy was introduced. During pregnancy her scalp hair completely re-grew, and following gestation week 39 she delivered healthy female child.

CONCLUSION

Thyroid antibodies could contribute to previous recurrent abortions in our patient. It is suggested that in older primiparas with Hashimoto thyroiditis and history of RSA, a combined treatment with IVIg, anticoagulation and antiaggregation therapy should be considered.

Study on antiphospholipid/anticardioliplin antibodies in women with recurrent abortion

Background

Antiphospholipid antibodies are associated with recurrent abortion but correlation between level of antibodies and gestational age of abortion and duration post abortion is not clear.

Objectives

Aim of this study was study on relation between antiphospholipid antibodies in women with recurrent abortion and their gestational age and duration post abortion.

Patients and Methods

We performed a case-control study on 197 pregnant women who had history of spontaneous recurrent abortion as case group and 50 pregnant healthy women as control group. Demographic characteristic of all participants filled in questionnaire forms. Antipospholipid and anticardiolipin antibodies were measured in their serum by Enzyme linked Immunoassay with orgenec kits. Data analyzed by SPSS software (version 13) and T statistical test. P value less than 0.05 was considered significant.

Results

Mean age of participants was 24-39 years old. The average rate of antiphospolipid antibodies in patients with normal anticardiolipin was greater than those with abnormal anticardiolipin and T-test showed significant difference between two groups.(P = 0.000) In case group the number of abortions was more, mean of antiphosopolipid antibody levels were also higher. Mean anticardiolipin and antiphospholipid antibodies rate was greater with increasing gestational age at time of first abortion. Almost mean antipospholipid and anticardiolipin antibodies in all patients remained in high level just in first 5 years with any number of abortions and five years later, antibodies began to fall.

Conclusions

Antipospholipid antibodies based on number of abortions and gestational age of abortions were increased. Mean antipospholipid and anticardiolipin antibodies in all patients remained in high level just in first 5 years post abortion and then began to fall.

When conventional treatment fails: the role of intravenous immunoglobulin in recurrent pregnancy loss secondary to antiphospholipid syndrome

Recurrent pregnancy loss (RPL) is a well-recognized complication of antiphospholipid syndrome (APS). First line therapy consists of low dose aspirin and heparin. Despite conventional therapy some women fail to achieve a successful pregnancy outcome. We describe the case of a patient who had two live births following intravenous immunoglobulin therapy despite previous failure with conventional therapy for RPL in the setting of APS. We will summarize the available literature on intravenous immunoglobulin for this indication.

Mixed lymphocyte reaction blocking factors (MLR-Bf) as potential biomarker for indication and efficacy of paternal lymphocyte immunization in recurrent spontaneous abortion

OBJECTIVES

The majority of cases of unexplained recurrent spontaneous abortion (RSA) remains unclear and is found to be associated with alloimmune antibodies termed as mixed lymphocyte reaction blocking factor (MLR-Bf). The decreased production of MLR-Bf may play major role in the immunologic failure of pregnancy and can lead to abortion. The present study was aimed at evaluating MLR-Bf as potential biomarker of indication and the efficacy of immunotherapy with paternal lymphocytes (LIT) in women with RSA.

MATERIALS AND METHODS

A total of 97 women with history of unexplained RSA were recruited for this prospective study. These women showed negative for MLR-Bf and registered for lymphocyte immunotherapy with husband cells. Women with autoimmune pathology or anti-phospholipid syndrome were excluded. All individuals gave their consent to participate in the study.

RESULTS

We have analyzed MLR proliferative response and MLR-Bf in nonpregnant women with history of RSA before and after LIT. Following LIT, the initially low MLR proliferative response was restored at 76.6 % of women, and MLR-Bf activity in blood serum could be detected in 74 % of women. The rate of successful pregnancy was shown to be significantly higher in women positive for MLR-Bf (50/72) as compared with the MLR-Bf negative women (7/25; χ (2) = 0.0003).

CONCLUSION

The data obtained demonstrate that LIT with the paternal lymphocytes in MLR-Bf negative women is accompanied by increased proliferative cell response to the paternal alloantigens and by enhanced production of soluble suppressor activity factors (MLR-Bf) that is associated with improved pregnancy outcome in women with history of RSA.

Adaptive immune responses during pregnancy

It has long been believed that there is no immune interaction between mother and conceptus during pregnancy. This concept changed after evidence was provided that the maternal immune system is aware of the semiallogeneic conceptus and develops strategies to tolerate it. Since then, finely regulated mechanisms of active tolerance toward the fetus have been described. This Special Issue of the American Journal of Reproductive Immunology deals with these mechanisms. It begins with the description of minor histocompatibility antigens in the placenta; it further goes through adaptive immune responses toward paternal fetal antigens, mostly concentrating on regulatory T cells and molecules modulating the Th1/Th2 balance. The participation of antibody-producing B cells in normal and pathological pregnancies is also discussed. This introductory chapter resumes the concepts presented throughout the Issue and discusses the clinical applications raised from these concepts.

Loss of maternal annexin A5 increases the likelihood of placental platelet thrombosis and foetal loss

Antiphospholipid syndrome is associated with an increased risk of thrombosis and pregnancy loss. Annexin A5 (Anxa5) is a candidate autoantigen. It is not known, however, whether endogenous Anxa5 prevents foetal loss during normal pregnancy. We found significant reductions in litter size and foetal weight in Anxa5-null mice (Anxa5-KO). These changes occurred even when only the mother was Anxa5-KO. A small amount of placental fibrin deposition was observed in the decidual tissues, but did not noticeably differ between wild-type and Anxa5-KO mice. However, immunoreactivity for integrin beta 3/CD61, a platelet marker, was demonstrated within thrombi in the arterial canals only in Anxa5-KO mothers. Subcutaneous administration of the anticoagulant heparin to pregnant Anxa5-KO mice significantly reduced pregnancy loss, suggesting that maternal Anxa5 is crucial for maintaining intact placental circulation. Hence, the presence of maternal Anxa5 minimises the risk of thrombosis in the placental circulation and reduces the risk of foetal loss.

Repeated miscarriages in patients with antiphospholipid syndrome and subjected to in vitro fertilization: the importance of preimplantation genetic diagnosis

The aim of this study was to investigate two patients with antiphospholipid syndrome (APS) who suffered from multiple repeated pregnancy losses of probably genetically impaired embryos. Sera from these patients contained high levels of IgG antibodies against cardiolipin, IgG and IgM phosphatidyl inositol, IgG phosphatidyl L-serine, and IgG against anti-annexin V. The conventional treatment of APS was ineffective. Preimplantation genetic diagnosis (PGD) showed chromosomally impaired embryos. The course of pregnancies and deliveries were monitored due to the close collaboration of in vitro fertilization and PGD in early embryos. After the selection of normal embryos using PGD, and the treatment of APS, both patients became pregnant and delivered healthy babies. Without such selection, both women would probably have miscarried their embryos again.

A high dose intravenous immunoglobulin therapy for women with four or more recurrent spontaneous abortions

Recurrent spontaneous abortion (RSA) may have immunological etiology. The aim of this study was to assess the efficacy of a high dose intravenous immunoglobulin (HIVIg) therapy, in which 20 g of intact type immunoglobulin was infused daily for 5 days during early gestation, for women who had a history of four or more consecutive spontaneous abortions of unexplained etiology. A total of 60 pregnant RSA women underwent HIVIg therapy, and the pregnancy outcome was assessed. The live birth rate was 73.3% (44/60). Fifteen pregnancies ended in spontaneous abortion, and one ended in intrauterine fetal death. In 11 of the 15 spontaneous abortions, fetuses had abnormal chromosome karyotype. When the 11 pregnancies with abnormal chromosome karyotype were excluded, the live birth rate was as high as 89.8% (44/49). The HIVIg therapy may be effective for severe cases of unexplained RSA.

Induction of decreased fecundity by tetanus toxoid hyper-immunization in C57BL/6 mice depends on the applied adjuvant

It has already been shown that tetanus toxoid (TTd) hyper-immunization is a suitable experimental method for creating the animal model of antiphospholipid syndrome (APS) in BALB/c mice. The severity of APS pathology in BALB/c mice mainly correlates to the affinity of anti-β2 glycoprotein I (β2GPI) antibodies. In this study we have investigated reproductive pathology induced in C57BL/6 mice by TTd hyper-immunization using a combination of different pretreatments (complete Freund's adjuvant or glycerol) and adjuvants (alhydrogel or glycerol). A decrease in fecundity was recorded in only C57BL/6 mice immunized with alhydrogel adjuvant, irrespective of the kind of applied pretreatment; it was associated with an increase in abundance of low affinity anti-β2GPI IgG antibodies and Th1 prevalence.

Risk factors for pregnancy failure in patients with anti-phospholipid syndrome treated with conventional therapies: a multicentre, case-control study

OBJECTIVE

To identify the risk factors associated with pregnancy failure in patients with APS treated with conventional therapy.

METHODS

A multicentre, case-control study was conducted to compare APS patients with successful and unsuccessful pregnancy outcomes. We retrospectively considered 410 pregnancies of women diagnosed with primary APS. The study focused on 57 unsuccessful pregnancies (considered the study population) and 57 successful pregnancies (considered the control population) matched for age and therapy. All the patients had been treated with conventional protocol treatments including low-dose aspirin and/or heparin. The clinical and laboratory features of the two groups of women diagnosed with APS were compared.

RESULTS

The independent risk factors for pregnancy failure were: (i) the presence of SLE or other autoimmune diseases [odds ratio (OR) 6.0; 95% CI 1.7, 20.8; P = 0.01]; (ii) history of both thrombosis and pregnancy morbidity (OR 12.1; 95% CI 1.3, 115.3; P = 0.03); and (iii) triple [Immunoglobulin (Ig) G/IgM aCLs plus IgG/IgM anti-β(2) glycoprotein I antibodies plus LA] aPL positivity (OR 4.1; 95% CI 1.0, 16.7; P = 0.05). APS patients diagnosed on the basis of a single positive test and/or history of pregnancy morbidity alone were generally found to have successful pregnancies.

CONCLUSION

It would seem from these findings that the risk of pregnancy failure in APS women planning to conceive can be stratified on the basis of some specific clinical and laboratory features.

Impact of short-term preconceptional exposure to particulate air pollution on treatment outcome in couples undergoing in vitro fertilization and embryo transfer (IVF/ET)

PURPOSE

To assess the potential effects of short-term exposure to particulate air pollution during follicular phase on clinical, laboratory, and pregnancy outcomes of women undergoing IVF/ET.

METHODS

Retrospective cohort study of 400 first IVF/ET cycles of women exposed to ambient particulate matter during follicular phase. Particulate matter (PM) was categorized into quartiles (Q(1): < or =30.48 microg/m(3), Q(2): 30.49-42.00 microg/m(3), Q(3): 42.01-56.72 microg/m(3), and Q(4): >56.72 microg/m(3)).

RESULTS

Clinical, laboratory, or treatment variables were not affected by follicular phase PM exposure periods. Women exposed to Q(4) period during the follicular phase of conception cycles had a higher risk of miscarriage (odds ratio, 5.05; 95% confidence interval: 1.04-25.51) when compared to women exposed to Q(1-3) periods.

CONCLUSION

Our results show an association between brief exposure to high levels of ambient PM during the preconceptional period and early pregnancy loss, although no effect of this exposure on clinical, laboratory, and treatment outcomes was observed.