Immunologically mediated abortion (IMA)

Bias from conditioning on live birth in pregnancy cohorts: an illustration based on neurodevelopment in children after prenatal exposure to organic pollutants

Only 60-70% of fertilized eggs may result in a live birth, and very early fetal loss mainly goes unnoticed. Outcomes that can only be ascertained in live-born children will be missing for those who do not survive till birth. In this article, we illustrate a common bias structure (leading to 'live-birth bias') that arises from studying the effects of prenatal exposure to environmental factors on long-term health outcomes among live births only in pregnancy cohorts. To illustrate this we used prenatal exposure to perfluoroalkyl substances (PFAS) and attention-deficit/hyperactivity disorder (ADHD) in school-aged children as an example. PFAS are persistent organic pollutants that may impact human fecundity and be toxic for neurodevelopment. We simulated several hypothetical scenarios based on characteristics from the Danish National Birth Cohort and found that a weak inverse association may appear even if PFAS do not cause ADHD but have a considerable effect on fetal survival. The magnitude of the negative bias was generally small, and adjusting for common causes of the outcome and fetal loss can reduce the bias. Our example highlights the need to identify the determinants of pregnancy loss and the importance of quantifying bias arising from conditioning on live birth in observational studies.

Misoprostol treatment for early pregnancy failure does not impair future fertility

AIMS

To examine whether misoprostol treatment for first trimester missed abortion affects future fertility.

PATIENTS AND METHODS

In a historical prospective approach, we analyzed our database for patients treated with misoprostol. All eligible patients underwent an interview according to a questionnaire, which includes their demographic characteristics, obstetric, gynecologic and infertility history. They were asked about the side effects, intention and subsequent ability to conceive. Their future pregnancy rates were calculated and compared to the acceptable figures in the literature.

RESULTS

The infertility rates among our patients were similar to those reported in the general population. Pregnancy rates 2 years after treatment were similar to the previously published reports, except for lower rates during the first three months post-treatment. Although no between-group differences were observed in the subsequent pregnancy rates, 2 years following misoprostol treatment in ≤35 versus >35 years old patients, primi- versus multigravida and nulli- versus parous women, higher pregnancy rates were observed in patients ≤35 versus >35 years old, primi- versus multigravida and nulli- versus, parous, during the first 3 months following misoprostol treatment.

CONCLUSION

Misoprostol treatment, for women with first trimester missed abortion and favorable reproductive history, is an acceptable treatment with no detrimental effect on future fertility.

Tumor necrosis factor-308 polymorphism increases the embryo implantation rate in women undergoing in vitro fertilization

STUDY QUESTION

Do TNF-308 and -238 polymorphisms impact the embryo implantation rate after in vitro fertilization (IVF) in women without female infertility factor?

SUMMARY ANSWER

The presence of the TNF-308A allele is associated with high implantation and multiple pregnancy rates in women without known infertility factors after ovarian hyperstimulation with exogenous FSH.

WHAT IS ALREADY KNOWN

Multiple pregnancies are frequent after the use of Assisted Reproductive Technologies. Single embryo transfer (SET) has been proposed as a simple way to prevent these risks. However, the extension of SET indications to patients not selected based on specific criteria is controversial because of reduced pregnancy rates. To date, the predictive value of the parameters used for SET (age, gynecological history of the patient and uterine characteristics) allows a pregnancy rate of ~30%.

STUDY DESIGN, SIZE, DURATION

The potential predictive value of TNF polymorphisms (-308, rs1800629 and -238, rs361525) on implantation rate was evaluated in 424 women requiring IVF due to male fertility factors. This cohort retrospective study was conducted over 4 years in University-affiliated hospitals.

PARTICIPANTS, SETTING, METHODS

The entire patient group included 424 women undergoing intracytoplasmic sperm injection (ICSI) due to male fertility factors without the contribution of any female factor. From among this group, a selected patient group included 120 women with a normal karyotype, age under 38 years, serum follicle-stimulating hormone (Day-3 FSH) levels below 10 IU/l, a long agonist desensitization protocol associated with recombinant FSH treatment and a Caucasian background.

MAIN RESULTS AND THE ROLE OF CHANCE

The TNF-238 polymorphism was not associated with implantation rate. In contrast, the presence of the TNF-308A allele was associated with increased Day 3-E2 levels as well as higher implantation and multiple pregnancy rates after fresh embryo transfer in women from the entire and selected patient groups. Moreover, in the selected patient group, the presence of the TNF-308A allele was also associated with a decrease in the miscarriage rate. The benefit of the TNF-308A allele in predicting implantation rates was not observed after the use of frozen embryos.

LIMITATIONS, REASONS FOR CAUTION

Future studies are needed to evaluate whether the TNF-308A allele might also be a biomarker in women with infertility factors.

WIDER IMPLICATIONS OF THE FINDING

The TNF-308A allele may represent a good candidate for a potential predictive, non-invasive biomarker in the SET strategy. However, its impact should be evaluated in prospective studies.

STUDY FUNDING/COMPETING INTEREST

This study was conducted with financial support from the French Institute for Health and Medical Research (INSERM), Organon France for a FARO (Fond d'Aide à la Recherche Organon) fellowship (to V.T.) and CHU Nice PHRC (PHRC 09-279).There are no competing interests.

Unexplained fetal death has a biological signature of maternal anti-fetal rejection: chronic chorioamnionitis and alloimmune anti-human leucocyte antigen antibodies

AIMS

Chronic chorioamnionitis is a histological manifestation of maternal anti-fetal cellular rejection. As failure of graft survival is the most catastrophic event in organ transplantation, we hypothesized that fetal death could be a consequence of maternal rejection. The aim of this study was to assess whether there is evidence of cellular and antibody-mediated rejection in fetal death.

METHODS AND RESULTS

Placental histology was reviewed for the presence of chronic chorioamnionitis in unexplained preterm fetal death (n=30) and preterm live birth (n=103). Amniotic fluid CXCL10 concentrations were measured with a specific immunoassay. Chronic chorioamnionitis was more frequent in fetal death than in live birth (60.0% versus 37.9%; P<0.05) and fetal death had a higher median amniotic fluid CXCL10 concentration than live birth (2.0 versus 1.8 ng/ml, P<0.05), after adjusting for gestational age at amniocentesis. Maternal anti-human leucocyte antigen class II panel-reactive seropositivity determined by flow cytometry was higher in fetal death compared to live birth (35.7% versus 10.9%; P<0.05).

CONCLUSIONS

Chronic chorioamnionitis is a common pathologic feature in unexplained preterm fetal death. This novel finding suggests that cellular and antibody-mediated anti-fetal rejection of the mother is associated with fetal death (graft failure) in human pregnancy.

The influence of the environment and other exogenous agents on spontaneous abortion risk

It is estimated that close to 30% of all pregnancies end in spontaneous abortion. Although about 60% of spontaneous abortions are thought to be due to genetic, infectious, hormonal, and immunological factors, the role of the environment remains poorly understood. Pregnancy involves a delicate balance of hormonal and immunological functions, which may be affected by environmental substances. Many toxic substances that are persistent in the environment and accumulate in the fatty tissues may disrupt this equilibrium. This overview addresses known risk factors for spontaneous abortions and examines the role, if any, that environmental factors (chemical and physical) may play in the etiology of this adverse health outcome.

Human autoantibodies recognizing human and mouse preimplantation stages

PROBLEM

To find out whether autoantibodies against human preimplantation stages are present in some human sera and, if so, whether the antibodies could be capable to affect the egg development and/or to trigger an activation of the complement system at the procedures of assisted conception.

METHODS

1. Immunohistochemistry on blots of human preimplantation stages. 2. Immunohistochemistry on paraffin sections of human and mouse preimplantation stages. 3. Culture of mouse morulae to analyze complement activation.

RESULTS

1. Some human sera contained autoantibodies against human preimplantation stages. 2. Human-mouse cross-reacting antibodies against preimplantation stages occurred. 3. Immune complexes, formed on mouse preimplantation stages, activated the complement systems in egg cultures, resulting in a damaging of the eggs.

CONCLUSION

The presence of natural autoantibodies to preimplantation stages may be associated with reproduction failure, caused by a direct effect by the autoantibodies and/or an activation of the uterine complement system by the immune complexes formed.

Decidua as a site of extrathymic V gamma I T-cell differentiation

PROBLEM

Decidual tissue is an interface between the host and fetus, which is regarded as a natural allograft. We have reported the possible presence of extrathymic T cells in human decidua through the expression of recombinase-activating genes in the decidual CD16-CD56bright large granular lymphocytes.

METHODS

In this study we analyzed expression of TCR V gamma delta gene segments in peripheral lymphocytes and decidual and nonpregnant endometrial samples using RT-PCR and oligonucleotide hybridization.

RESULTS

Interestingly, a limited repertoire of V gamma gene segments were discovered in decidual lymphocytes of normal pregnancy when compared with peripheral lymphocytes, whereas usage of V delta gene segments were ubiquitous in peripheral and decidual lymphocytes. Strong expression of V gamma I gene segment, often exceeding 50% of total V gamma, were noted in all (13/13) pregnant decidual tissues obtained at different gestational stages. Interestingly, this predominance of V gamma I gene is also noted in nonpregnant endometrial samples and the decidua of patients with ectopic pregnancies.

CONCLUSIONS

Our results suggest the nature of decidual V gamma I T cells as possible suppressors of rejective maternal cytotoxic T cells during the maintenance of normal pregnancies.