Endocrinology of recurrent pregnancy loss

Following implantation, the maintenance of the pregnancy is dependent on a multitude of endocrinological events that will eventually aid in the successful growth and development of the fetus. Although the great majority of pregnant women have no pre-existing endocrine abnormalities, a small number of women can have certain endocrine alterations that could potentially lead to recurrent pregnancy losses. It is estimated that approximately 8 to 12% of all pregnancy losses are the result of endocrine factors. During the preimplantation period, the uterus undergoes important developmental changes stimulated by estrogen, and more importantly, progesterone. Progesterone is essential for the successful implantation and maintenance of pregnancy. Therefore, disorders related to inadequate progesterone secretion by the corpus luteum are likely to affect the outcome of the pregnancy. Luteal phase deficiency, hyperprolactinemia, and polycystic ovarian syndrome are some examples. Several other endocrinological abnormalities such as thyroid disease, hypoparathyroidism, uncontrolled diabetes, and decreased ovarian reserve have been implicated as etiologic factors for recurrent pregnancy loss.     

Antiphosphatidylethanolamine antibodies in recurrent early pregnancy loss and mid-to-late pregnancy loss

AIM: Associations have been reported between antiphospholipid antibodies (aPL), mainly anticardiolipin antibodies (aCL) and/or the lupus anticoagulant, and recurrent pregnancy losses (RPL). However, relatively few studies describing antiphosphatidylethanolamine antibodies (aPE) have been reported. We describe the prevalence of aPL to both cardiolipin and phosphatidylethanolamine in patients with RPL. METHODS: Patients with recurrent early pregnancy losses (n = 145) and mid-to-late pregnancy loss(es) (n = 26) were screened for aPE and aCL. RESULTS: In patients with recurrent early pregnancy losses, prevalence of immunoglobulin G (IgG) aPE (17.9%, P = 0.001) and immunoglobulin M (IgM) aPE (12.4%, P = 0.01) was significantly higher than in the control group. In patients with mid-to-late pregnancy loss(es), prevalence of IgM aPE (19.2%, P = 0.008) and IgG aCL (23.1%, P = 0.02) was significantly higher than in the control group. CONCLUSION: Our data suggest that aPE may be a risk factor in patients with mid-to-late pregnancy loss(es) as well as recurrent early pregnancy losses.     

Management of recurrent early pregnancy loss

Recurrent pregnancy loss is a devastating health problem that affects many couples who are trying to establish a family. Evaluation depends on a number of factors, including the pattern of pregnancy loss, underlying medical disease and life-style issues. A detailed obstetric history, including gestational age at the time of death, ultrasound, pathology and cytogenetic results, is key in the evaluation and management of recurrent pregnancy loss. This complex reproductive disorder requires a multidisciplinary approach since genetic, endocrinologic, anatomic, immunologic, infectious, thrombophilic and iatrogenic factors may require evaluation and management. Monitoring of subsequent pregnancies requires close supportive care.     

Evaluation and management of recurrent early pregnancy loss

Recurrent pregnancy loss affects up to 5% of couples trying to establish a family. Evaluation classically begins after 3 consecutive miscarriages of less than 10 weeks of gestation but may be warranted earlier if a prior miscarriage was found to be euploid, or if there is concomitant infertility and/or advancing maternal age. The evaluation begins with an extensive history and physical, followed by a diagnostic screening protocol. Management must be evidence-based; unproven treatments should be avoided. If no factor is identified, many couples will still eventually have a successful pregnancy outcome with supportive therapy alone.     

Hyperhomocysteinemia and recurrent early pregnancy loss: a meta-analysis

Objective: To quantify the risk of recurrent early pregnancy loss in the presence of elevated fasting or afterload homocysteine concentrations or homozygosity for the 677C→T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene (T/T genotype).

Design: Case-control studies published between January 1992 and November 1999 were identified with a MEDLINE-search. These studies were combined with a recent case-control study performed by our own research group.

Setting: Academic research environment.

Patient(s): Studies published in the English language, concerning two or more pregnancy losses before 16 weeks’ menstrual age were included.

Intervention(s): Meta-analysis of all of the studies included.

Main Outcome Measure(s): The number of subjects with and without hyperhomocysteinemia or with the T/T genotype were derived, if necessary the study was supplemented by personal communication with the original authors.

Result(s): Pooled risk estimates of 2.7 (1.4 to 5.2) and 4.2 (2.0 to 8.8) were calculated for fasting and afterload plasma homocysteine concentrations, respectively. For the MTHFR T/T genotype a pooled risk estimate of 1.4 (1.0 to 2.0) was found.

Conclusion(s): These data support hyperhomocysteinemia as a risk factor for recurrent early pregnancy loss. Further research should be focused on the pathophysiology of this relationship and on the clinical efficacy of B vitamin supplementation.     

Thrombophilia and recurrent pregnancy loss

Many unanswered questions regarding thrombophilia and recurrent pregnancy loss exist. For example, does a true association exist? Are thrombotic mechanisms relevant? Is a second messenger necessary to cause the manifestation of thrombosis? At present it seems that thrombophilia are associated with and may even cause some cases of pregnancy loss. The role of treatment remains to be determined. Although the aim of physicians working in this field is entirely laudable, to allow childless couples to have children, it is necessary to have good evidence of effect before treatment is given to all patients. A serious ethical dilemma remains, however, namely should treatment that may be effective be denied to patients who have prior pregnancy losses? Denial of treatment is extremely distressing for the patient and the physician. The author's own practice is to offer treatment after a full explanation, particularly because treatment is generally prescribed in the antiphospholipid syndrome and justified in hereditary thrombophilias according to the report of Carp and colleagues, showing a 25% improvement in live birth rates in treated patients. When treatment fails, however, the embryo should be karyotyped to exclude chromosomal aberrations.     

Endometriosis and recurrent pregnancy loss

A possible association between endometriosis and spontaneous abortion has been suggested in mostly uncontrolled and/or retrospective studies. Some controlled studies evaluating the association between endometriosis and spontaneous abortion showed important methodological shortcomings: heterogeneity between cases and controls, analysis of the abortion rate before the diagnosis of endometriosis, and selection bias of study and control groups. On the basis of controlled prospective studies, there is no evidence that endometriosis is associated with (recurrent) pregnancy loss or that medical or surgical treatment of endometriosis reduces the spontaneous abortion rate. In programs of assisted reproduction, some studies have shown that the number and quality of oocytes, the fertilization rate, and the implantation rate per embryo may be reduced in women with endometriosis, but this observation has not been confirmed by other investigators. Future studies evaluating the reproductive outcome of patients with endometriosis in assisted reproduction programs should include reliable information about the date and histological confirmation of the diagnosis of endometriosis, time interval between treatment with assisted reproduction and the last laparoscopy, possible recurrence of endometriosis, effectiveness of interim hormonal (suppressive) therapy, accuracy of ultrasound diagnosis, and accuracy of "negative" diagnosis.     

Clinical assessment and management of the endometrium in recurrent early pregnancy loss

Unexplained and recurrent loss of pregnancies is a heartbreaking and frustrating condition. The routine diagnostic workup for pregnancy loss includes hormonal evaluation, screening for genetic or chromosomal defects, immunologic and thrombophilic testing, and evaluation of congenital or acquired Müllerian defects. In cases of idiopathic pregnancy loss, defects in endometrial receptivity are increasingly being investigated. The role of the endometrium in pregnancy loss has historical roots but remains controversial. Exciting new directions based on microRNAs, proteomics, and epigenetics promises to keep this area of investigation both interesting and complex. With each new diagnostic and therapeutic biomarker identified comes a greater potential for diagnosis and treatment of women. The clinical assessment of the endometrium remains an important part of the investigation of couples with unexplained pregnancy loss.     

Homocysteine and folate levels as risk factors for recurrent early pregnancy loss

OBJECTIVE: To estimate the relative risk of recurrent early pregnancy loss for different total plasma homocysteine and serum folate concentrations. METHODS: In a case-control study, we measured homocysteine (fasting and afterload), folate (serum and red cells), pyridoxal 5'-phosphate, and cobalamin concentrations in 123 women who had at least two consecutive spontaneous early pregnancy losses each and compared concentrations with those of 104 healthy controls. RESULTS: Women with recurrent early pregnancy losses had significantly lower serum folate concentrations than controls, whereas the other measurements were similar to those of controls. Elevated homocysteine, fasting greater than 18.3 micromol/L and afterload greater than 61.5 micromol/L, was a risk factor for recurrent early pregnancy loss, with odds ratios (ORs) and 95% confidence intervals (95% CIs) of 3.6 (1.2, 12.7) and 2.7 (0.9, 8.8) in the group with recurrent miscarriages: 6.4 (1.9, 24.3) and 4.3 (1. 2, 17.3) in primary aborters, and 4.2 (1.3, 15.4) and 3.4 (1.0, 12. 8) in those with three or more miscarriages. The ORs (95% CIs) in the same study populations for serum folate concentrations less than 8.4 nmol/L were 2.1 (0.9, 4.8), 2.7 (1.0, 7.8), and 3.2 (1.3, 8.1), respectively. A significant dose-response relationship between serum folate concentrations and risk of recurrent early pregnancy loss suggested a protective effect by high serum folate concentrations. CONCLUSION: Elevated homocysteine and reduced serum folate concentrations were risk factors for recurrent spontaneous early pregnancy losses. Folic acid supplementation might be beneficial in women with histories of early pregnancy loss.     

Sperm aneuploidy and recurrent pregnancy loss

Experiments of double target in-situ hybridization were performed separately for chromosomes 1-17, 8-18 and sex chromosomes on sperm samples from 20 couples suffering from three or more recurrent first trimester abortions. For a subset of this study population, additional experiments of multicolour fluorescence in-situ hybridization for chromosomes 4, 7, 12, 13, 15, 18, 21, and 22, were performed on the bases of the available data from abortive tissue karyotyping. A markedly high rate of sperm disomy (14.5-15.5%) was scored in only two cases. For three other patients, the cumulative disomy rates for chromosomes 1, 17, 8, 18, X and Y also increased but at a lower level (7.8-9.5%). For the remaining 15 patients, the frequency of sperm aneuploidy was moderately increased or normal. Men with recurrent pregnancy loss (RPL) and poor semen quality had baseline sperm aneuploidy and diploidy rates higher than men with normal semen parameters (with or without RPL). Using probes for chromosomes 1, 17, 8, 18, X and Y, significantly elevated frequencies of sperm aneuploidy (not diploidy) were found in 10% of men with a history of RPL. Their rate of sperm aneuploidy was 30-34%. For the other men, changes in sperm aneuploidy were not thought to affect RPL. Poor semen quality per se impacted negatively on sperm aneuploidy and diploidy, thus making the interpretation of clinical data more difficult.     

Uterine anomaly and recurrent pregnancy loss

Women with recurrent pregnancy loss have a 3.2 to 6.9% likelihood of having a major uterine anomaly and a 1.0 to 16.9% chance of having an arcuate uterus. Bicornuate and septate uterine have a negative impact on reproductive outcomes and are associated with subsequent euploid miscarriage. The impact of an arcuate uterus on pregnancy outcome remains unclear. There are no definitive criteria to distinguish among the arcuate, septate, and bicornuate uteri. The American Fertility Society classification of Müllerian anomalies is the most common standardized classification of uterine anomalies. According to estimates, 65 to 85% of patients with bicornuate or septate uteri have a successful pregnancy outcome after metroplasty. However, 59.5% of the patients with such anomalies have a successful subsequent pregnancy without surgery, with a cumulative live birthrate of 78.0%. There is no case-control study to compare live birthrates in women who had surgery compared with those who did not. Strict criteria to distinguish between the bicornuate and septate uterus should be established. Further study is needed to confirm the benefits of metroplasty.     

Sporadic pregnancy loss and recurrent miscarriage

Progesterone is essential for the maintenance of pregnancy, and progesterone deficiency is associated with miscarriage. The subject of whether progesterone supplementation in early pregnancy can prevent miscarriage has been a long-standing research question and has been investigated and debated in the medical literature for over 70 years. During this time, several different progestogens have been synthesised and tested for the prevention of miscarriage. In this chapter, we describe the prior evidence alongside the latest research using micronized natural progesterone as well as synthetic progestogens, which were used to treat both recurrent and threatened miscarriage. The totality of evidence indicates that women with a past history of miscarriage who present with bleeding in early pregnancy may benefit from the use of vaginal micronized progesterone. The clinical implications of the findings are discussed.     

Immunotherapy for recurrent pregnancy loss

When immunomodulation is used on an unselected population with recurrent miscarriage (RM), there is no improvement in the live birth rate. However, when the population is selected for a poor prognosis, or immune phenomena, immunotherapy has been shown to be effective. This review discusses four immunomodulatory agents, namely, paternal leukocyte immunization, intravenous immunoglobulin (IVIg), intralipid, and filgrastim. The presence of embryonic aneuploidy may confound the results of treatment, therefore creating an impression of futility when treatment may be highly effective in saving pregnancies that can be saved. Additionally, in an unselected population with RM, there is a relatively good prognosis of 60–80% for a subsequent live birth depending on whether the definition of ≥2 or ≥3 miscarriages is used. Hence, spontaneous prognosis must be taken into account, which has not been the case in previous trials.This review discusses the possible immune-mediated mechanisms of pregnancy loss and the means whereby immunotherapy may modulate these mechanisms.     

Cytokines in recurrent pregnancy loss

Cytokines seem to play a critical role in the pathogenesis of unexplained recurrent pregnancy loss (RPL). Th1 cytokines have been shown to exert deleterious effects on pregnancy, inhibiting foetal growth and development. On the other hand, Th2 cytokines have been associated with successful pregnancy. The purpose of this study was to evaluate cytokine production in women with RPL. The studied group comprised 29 women with RPL, with at least three consecutive spontaneous abortions. The control group included 27 women with a history of successful pregnancies and no miscarriage. We determined IL-6 and TNF-alpha production in peripheral blood cultured with LPS, as well as IFN-gamma and TGF-beta induced by PHA stimulation. Cytokines were measured by enzyme-linked immunoabsorbant assay (ELISA) using commercial kits (RD, Amersham-Pharmacia). Mann-Whitney test was applied to compare differences between groups. The level of significance was defined at P < 0.05. We observed significantly higher levels of IFN-gamma (355.8 pg/ml versus 98.0 pg/ml; P = 0.01) and a trend toward increased TNF-alpha production (2410.2 pg/ml versus1980.2 pg/ml; P = 0.07) in RPL women as compared to controls. In relation to IL-6 and TGF-beta, no significant difference was detected between RPL and control groups. In agreement with experimental observations, our data support the hypothesis of Th1 cytokine involvement in the pathogenesis of RPL.