Risk factors for placenta accreta spectrum in pregnancies conceived after frozen-thawed embryo transfer in a hormone replacement cycle.

OBJECTIVE: Assisted reproductive technology (ART), especially frozen-thawed embryo transfer (FET) in a hormone replacement cycle (HRC), is a risk factor for placenta accreta spectrum (PAS). This study aimed to clarify the risk factors for PAS related to the maternal background and ART techniques in pregnancies achieved after FET in an HRC. STUDY DESIGN: We performed a case-control study in two tertiary perinatal centres in Japan. Among 14,028 patients who delivered at ≥24 weeks of gestation or were transferred after delivery to two tertiary perinatal centres between 2010 and 2021, 972 conceived with ART and 13,056 conceived without ART. PAS was diagnosed on the basis of the FIGO classification for the clinical diagnosis of PAS or retained products of conception after delivery at ≥24 weeks of gestation. We excluded women with fresh embryo transfer, FET with a spontaneous ovulatory cycle, a donor oocyte cycle, and missing details of the ART treatment. Finally, among women who conceived after FET in an HRC, 62 with PAS and 340 without PAS were included in this study. Multivariate logistic regression models were used for case-control comparisons, with adjustment for maternal age at delivery, parity, endometriosis or adenomyosis, the number of previous uterine surgeries of caesarean section, myomectomy, endometrial polypectomy or endometrial curettage, placenta previa, the stage of transferred embryos, and endometrial thickness at the initiation of progestin administration. RESULTS: PAS was associated with ≥2 previous uterine surgeries (adjusted odds ratio, 3.57; 95 % confidence interval, 1.60-7.97) and the stage of embryo transfer (blastocysts: adjusted odds ratio, 2.89; 95 % confidence interval, 1.15-7.26). In patients with <2 previous uterine surgeries, PAS was associated with an endometrial thickness of <7.0 mm (adjusted odds ratio, 5.18; 95 % confidence interval, 1.10-24.44). CONCLUSION: Multiple uterine surgeries and the transfer of blastocysts are risk factors for PAS in pregnancies conceived after FET in an HRC. In women with <2 previous uterine surgeries, a thin endometrium before FET is also a risk factor for PAS in these pregnancies.

Identifying optimal puncture position by a real-time image analysis for Piezo-ICSI: a prospective randomized sibling oocyte study.

RESEARCH QUESTION: Would the use of the intracytoplasmic sperm injection (ICSI) position detector (IPD) make it possible to identify the optimal puncture position on oolemma during Piezo-ICSI and reduce oocyte degeneration and unintentional membrane rupture (UMR)? DESIGN: This sibling oocyte study included 917 inseminated oocytes from 113 infertile patients undergoing Piezo-ICSI. Oocytes were randomly divided into two groups: with or without IPD. The rates of UMR, degeneration, fertilization and embryonic development were compared between the two groups. As a secondary analysis, non-IPD oocytes were retrospectively assessed as appropriate or non-appropriate injection sites and analysed alongside prospective 'appropriate' injections. RESULTS: The rates of UMR (7.0% versus 12.9%, P = 0.004) and degeneration (2.4% versus 6.1%, P < 0.01 = 0.008) were significantly lower in the IPD group than in the non-IPD group. No significant differences, however, were observed in the rates of fertilization (two pronuclei, 83.8% versus 78.9%), blastocyst formation (48.5% versus 48.8%) or good-quality blastocysts (22.5% versus 20.5%). Additionally, no significant differences were observed in the rates of pregnancy (29.4% versus 35.1%) or live births (26.5% versus 29.7%) in a single embryo transfer setting with or without IPD. Comparing all 'appropriate' injections with 'non-appropriate' injections also showed a significantly decreased rate of UMR and degeneration (both P ≤ 0.001). CONCLUSIONS: The present study demonstrated that a real-time image analysis during Piezo-ICSI markedly reduced oocyte degeneration by avoiding areas associated with a high risk of UMR. Therefore, IPD may increase the number of embryos available for treatment.

Optimal puncture position for ICSI can be detected by image analysis using Local Binary Pattern.

RESEARCH QUESTION: One of the problems during the intracytoplasmic sperm injection (ICSI) procedure is unintentional membrane rupture (UMR), which often predisposes to subsequent oocyte degeneration. Can the ICSI Position Detector (IPD) be useful in identifying the optimal puncture location to prevent UMR during ICSI? DESIGN: A total of 709 mature oocytes were included. Conventional ICSI was carried out and images were recorded by IPD; these were analysed retrospectively. RESULTS: Inseminated oocytes were retrospectively grouped according to the IPD, irrespective of whether oolemma was punctured at an area in which UMR is likely (non-appropriate group) or unlikely (appropriate group). In the appropriate group, rates of UMR (5.3% versus 18.2%) and degeneration (2.5% versus 8.7%) were significantly lower than those of the non-appropriate group, whereas rate of fertilization (87.1% versus 69.7%) was significantly higher than those of the non-appropriate group, respectively (P < 0.001). These differences remained even after propensity score matching to adjust for potential differences in characteristics between appropriate and non-appropriate groups. CONCLUSIONS: This study demonstrated that the IPD is useful to identify the optimal puncture location to circumvent UMR during the ICSI procedure, resulting in reduced UMR and oocyte degeneration, thereby, generating more embryos available for transfer or cryopreservation.

Clinical relevance of a newly developed endometrial receptivity test for patients with recurrent implantation failure in Japan.

Purpose: To assess the clinical efficacy of personalized embryo transfer (pET) guided by a new endometrial receptivity test, ERPeakSM, in patients with recurrent implantation failure (RIF). Methods: Recurrent implantation failure patients of all ages at two private Japanese clinics from April 2019 to June 2020 were retrospectively analyzed. The intervention group (n = 244) received pET in accordance with endometrial receptivity testing results and was compared to control group (n = 306) receiving standardized timing, non-personalized embryo transfer (npET). In propensity score matching analysis, the clinical pregnancy rate (CPR) and live birth rate (LBR) were compared between groups, and a subanalysis of advanced maternal age (AMA) (≥38 years old) versus non-AMA (<38 years old) patients was also conducted. Results: The CPR and LBR of the pET group were significantly higher than those of the npET group (37.7% vs. 20.0%, adjusted OR: 2.64; 95%CI, 1.70-4.11, p < 0.001 and 29.9% vs. 9.7%, adjusted OR: 4.13; 95%CI, 2.40-7.13, p < 0.001, respectively). Furthermore, in the subanalyses, the CPR and LBR of the pET group were significantly higher than those of the npET group in both the AMA non-AMA patients. Conclusions: The new ERPeakSM endometrial receptivity test is a useful alternative diagnostic tool for poor-prognosis patients, regardless of age.

Falloposcopic tuboplasty: an easy, quick, and safe technique.

OBJECTIVE: To describe our simplified technique for falloposcopic tuboplasty (FT) and demonstrate its principle and results. DESIGN: A step-by-step description of the technique and demonstration of its principle using a clay model. SETTING: Private infertility clinics in Osaka and Tokyo operated by 10 physicians. PATIENT(S): A total of 431 infertile women with a diagnosis of unilateral or bilateral proximal tubal occlusion (6 cm from the uterotubal ostia), between October 2013 and February 2019 were included. These patients underwent routine work-ups for infertility, including a semen analysis, hysterosalpingography, antimüllerian hormone, basal luteinizing hormone/follicle-stimulating hormone and prolactin concentrations during menstruation, postcoital test in the periovulatory period, and estradiol and progesterone concentrations in the middle of the luteal phase. Physicians performed hysterosalpingography to evaluate tubal patency and uterine shape. Saline infusion sonography was not conducted because it does not accurately identify regions of tubal occlusion and/or stenosis. INTERVENTION(S): The principle of our simplified technique for FT is that a hole is located at the side of the FT catheter tip. Therefore, the balloon and fiberscope move away from the catheter line (Fig. 1). The uterotubal ostium is located at the tip-end of the triangle of the uterine cavity. When a balloon is inserted while visualizing the uterotubal ostium at the nearest position to the ostium, the balloon hits the uterine wall. When a balloon is inserted 5-10 mm from the uterotubal ostium without visualization, the balloon may be easily placed in the ostium through its convex angle, allowing it to slide into the uterine wall (Figs. 2 and 3). Step 1: Confirm anteflexion or retroflexion of the uterus by ultrasound. Step 2: Confirm the direction of the uterotubal ostia by hysteroscopy. Step 3: Adjust the angle of the FT catheter according to steps 1 and 2, insert the catheter into the end of the uterus, pull it back 5-10 mm (without visualizing the uterotubal ostia), and then fix it to the forceps. Catheter placement away from the tubal ostium is confirmed by the residual length of the moving part of the catheter. An attending instructor should ask the operator about the feeling of rigidity when the catheter does not advance and then suggest whether to proceed or stop. In the latter case, the catheter is not moved, saline is infused for 1 minute for lubrication, the balloon is pulled back using the fiberscope to remove the bunching of the balloon, and balloon pressure is changed as follows: 6→8→6→10→6 mmHg. Our institutional review board stated that approval was not required because the video describes the technique of our routine procedure. MAIN OUTCOME MEASURE(S): A description of the FT technique using a clay model and a demonstration of its application in our clinic. RESULT(S): The average operative time was 15.4 minutes, and the clinical pregnancy rate was 24.4% (natural conception and intrauterine insemination without in vitro fertilization). No significant differences were observed in the operative time or pregnancy rate among physicians. Approximately 17 FT procedures may be performed using one fiberscope. CONCLUSION(S): Our simplified technique, which was described and demonstrated in this video article, is a feasible and practical approach for performing FT. It provides excellent cost performance by saving fiberscopes. The most important point is "Introduce the balloon and fiberscope 5-10 mm away from the uterotubal ostia without visualizing it." To facilitate learning this technique, we recommend watching the video and then practicing FT without searching for the uterotubal ostia. Physicians master FT without any assistance by an attending instructor in ≤3 attempts.

Chromosomal copy number analysis of products of conception by conventional karyotyping and next-generation sequencing.

PURPOSE: Chromosomal abnormalities are a major cause of spontaneous abortion, and conventional G-banded karyotyping (G-banding) is mainly utilized for chromosomal analysis. Recently, next-generation sequencing (NGS) has been introduced for chromosomal analysis. Here, we aimed to investigate the applicability and utility of NGS-based chromosomal analysis of products of conception (POC) on chorionic villus samples from spontaneous abortion. METHODS: The results of chromosomal analysis of 7 chorionic villus samples from spontaneous abortion were compared between conventional G-banding and NGS-based chromosomal copy number analysis. Age dependency and frequency of each chromosomal aneuploidy were evaluated for 279 cases analyzed by NGS. RESULTS: Excluding two cases (culture failure and maternal cell contamination), the results were consistent between G-banding and NGS. For cases analyzed by NGS, the rate of chromosomal abnormality increased in a maternal age-dependent manner. The frequency of each chromosomal aneuploidy detected by NGS was almost the same as that previously reported. Finally, NGS analysis was possible for difficult cases by G-banding analysis, such as culture failure, maternal cell contamination, long-term storage cases, and low cell number. CONCLUSIONS: Chromosome analysis using NGS not only obtains comparable results to conventional G-banding, but also can analyze POC more accurately and efficiently.

Clinical outcomes of microdissection testicular sperm extraction and intracytoplasmic sperm injection in Japanese men with Y chromosome microdeletions.

PURPOSE: We investigated the clinical results of Japanese men with Y chromosome microdeletions. METHODS: This study retrospectively examined 2163 azoospermic or severe oligozoospermic patients. We investigated the frequency of azoospermia factor (AZF) deletions and sperm retrieval rate (SRR) by microTESE in patients with these deletions, then analyzed the ICSI outcomes. RESULTS: Azoospermia factor deletions were found in 201 patients. SRR was significantly higher than that of the control group (74.0% vs 20.4%, P < .001). Thirty-three couples underwent ICSI using testicular spermatozoa retrieved by microTESE, and eight couples underwent ICSI using ejaculatory spermatozoa. The fertilization rate and clinical pregnancy rate per embryo transfer cycle were significantly higher in the ejaculatory group than that of the testicular group (66.4% vs 43.7%, P < .001, 53.3% vs 24.7%, P = .03, respectively). When compared with the control group, the fertilization rate was significantly lower in the testicular group with AZFc microdeletions (43.7% vs 53.6%, P < .001). CONCLUSIONS: Our study highlights that although microTESE in azoospermic men with AZFc microdeletions led to a higher SRR, ICSI outcomes of these men were worse than that of men without AZF deletions, even if testicular spermatozoa were retrieved.

Endometritis: new time, new concepts.

Endometritis is subdivided into two categories. Acute endometritis is symptomatic and characterized by microabscess formation and neutrophil invasion in the endometrial superficial epithelium, gland lumina, and uterine cavity. Chronic endometritis is rather silent and recognized as unusual plasmacyte infiltration in the endometrial stromal areas. Over the last decade, studies have disclosed the potential association between poor reproductive outcomes and endometritis, particularly chronic endometritis. The aim of this review is to address the current literature surrounding chronic endometritis and highlight recent advances in the research of this long-neglected gynecologic disease.

Minimum values for midluteal plasma progesterone and estradiol concentrations in patients who achieved pregnancy with timed intercourse or intrauterine insemination without a human menopausal gonadotropin.

OBJECTIVE: The aim of the study was to assess the lower limits of midluteal plasma progesterone and estradiol concentrations in patients who achieved pregnancy with timed intercourse or intrauterine insemination without a human menopausal gonadotropin stimulation. RESULTS: We included 297 pregnant cycles of 297 women and assessed midluteal plasma progesterone and estradiol concentrations and pregnancy outcomes, retrospectively. These cycles were compared with the non-pregnant cycles (406 cycles) of the same women who became pregnant. Mean midluteal plasma P4 and E2 concentrations were significantly (P < 0.01) higher in pregnant cycles (14.5 and 188.5 pg/mL) than in non-pregnant cycles (10.7 and 162.6 pg/mL). The 5 percentiles of progesterone and estradiol in pregnant cycles were 5.6 and 70.2 pg/mL, respectively. The lowest progesterone and estradiol levels in pregnant cycles were 2.3 and 23.4 pg/mL, respectively. In non-pregnant cycles, many women had low P4 levels that were less than 5.6 ng/mL. Subgroup analyses showed slight differences among the four groups, which may have been due to the ovarian function of each group. Miscarriage was not related to progesterone and estradiol concentrations. These values may be useful for the evaluation of necessary values for pregnancy with timed intercourse or intrauterine insemination.

Is a high serum copper concentration a risk factor for implantation failure?

BACKGROUND: Copper-containing contraceptive devices may deposit copper ions in the endometrium, resulting in implantation failure. The deposition of copper ions in many organs has been reported in patients with untreated Wilson's disease. Since these patients sometimes exhibit subfertility and/or early pregnancy loss, copper ions were also considered to accumulate in the uterine endometrium. Wilson's disease patients treated with zinc successfully delivered babies because zinc interfered with the absorption of copper from the gastrointestinal tract. These findings led to the hypothesis that infertile patients with high serum copper concentrations may have implantation failure due to the excess accumulation of copper ions. The relationship between implantation (pregnancy) rates and serum copper concentrations has not yet been examined. The Japanese government recently stated that actual copper intake was higher among Japanese than needed. Therefore, the aim of the present study was to investigate whether serum copper concentrations are related to the implantation (pregnancy) rates of human embryos in vivo. METHODS: We included 269 patients (age <40 years old) who underwent vitrifying and warming single embryo transfer with a hormone replacement cycle using good blastocysts (3BB or more with Gardner's classification). Serum hCG, copper, and zinc concentrations were measured 16 days after the first date of progesterone replacement. We compared 96 women who were pregnant without miscarriage at 10 weeks of gestation (group P) and 173 women who were not pregnant (group NP). RESULTS: No significant differences were observed in age or BMI between the groups. Copper concentrations were significantly higher in group NP (average 193.2 µg/dL) than in group P (average 178.1 µg/dL). According to the area under the curve (AUC) on the receiver operating characteristic curve for the prediction of clinical pregnancy rates, the Cu/Zn ratio (AUC 0.64, 95% CI 0.54-0.71) was a better predictor than copper or zinc. When we set the cut-off as 1.59/1.60 for the Cu/Zn ratio, sensitivity, specificity, the positive predictive value, and negative predictive value were 0.98, 0.29, 0.71, and 0.88, respectively. CONCLUSIONS: Our single-center retrospective study suggests that high serum copper concentrations (high Cu/Zn ratio) are a risk factor for implantation failure.

Relationship Between Fetal Loss and Serum Gonadal Hormones Level in Experimental Antiphospholipid Syndrome Mouse.

To investigate the effects of antiphospholipid antibodies on establishment of pregnancy and changes in hormones such as estradiol-17ß (E2) and progesterone (P) levels in circulation. Hence, mice were immunized with human ß2-Glycoprotein I (ß2GPI) and the effect of these antibodies on fetuses weight, placental obsrvation, Serum levels of P and E2 in pregnant mice, hematological were observed. Immunization of mice with human ß2-GPI resulted in elevated levels of antiphospholipid antibodies. The experimentally induced antiphospholipid syndrome mouse showed higher rate of fetal resorption, low number of viable fetuses, and "placental abnormalities". In these animals, serum E2 and P levels were reduced significantly. In addition, the blood cell variation among APS induced and control mice were determined. No significant variations were observed in number of Red Blood Cell count, White Blood Cell count and Hemoglobin content, while platelet number was significantly reduced as compared to control. These results clearly demonstrate that human ß2-GPI might be involved in causing gestational failure in APS by exerting their effect on serum hormones.

Live birth rate following oral antibiotic treatment for chronic endometritis in infertile women with repeated implantation failure.

PROBLEM: The aim of this prospective study was to investigate the prevalence of chronic endometritis (CE) in infertile women with a history of repeated implantation failure (RIF) and to determine whether oral antibiotic treatment improves their live birth rate in the following embryo transfer (ET) cycles. METHOD OF STUDY: Endometrial biopsy samples obtained from infertile women with RIF were subjected to immunohistochemistrical/histopathologic diagnosis of CE. Following antibiotic administration to the RIF/CE group, their histopathologic cure rate, microbial detection rate, and reproductive outcome in the subsequent ET cycles were prospectively studied. RESULTS: 33.7% of infertile women with RIF were diagnosed with CE. Following the first-line doxycycline treatment, the histopathologic cure rate in the subsequent endometrial biopsy was 92.3%. Following the second-line metronidazole/ciprofloxacin treatment, the overall cure rate was 99.1%. The live birth rate in the first ET cycle (P=.031, RR 1.48, 95% CI 1.03-2.12) and cumulative three ET cycles (P=.037, RR 1.39, 95% CI 1.02-1.90) following antibiotic treatment in the cured RIF/CE group (32.8% and 38.8%, respectively) was significantly higher than in the RIF/non-CE group (22.1% and 27.9%, respectively). CONCLUSION: Chronic endometritis was found in one-third of infertile women with RIF. The oral antibiotic treatment against CE might be a promising therapeutic option for infertile women with RIF.

Clinical background affecting pregnancy outcome following local endometrial injury in infertile patients with repeated implantation failure.

Local endometrial injury (LEI) has been performed as a promising medical intervention to improve the pregnancy outcome in infertile women suffering from repeated implantation failure (RIF) in in vitro fertilization-embryo transfer cycles. The effect of LEI, however, remains controversial. The aim of this retrospective study was to identify the subgroups of patients with RIF who benefit from LEI. We compared the clinical parameters between the patients who had had a clinical pregnancy in the subsequent embryo transfer cycle following the LEI cycle (LEI-CP group, n = 94) and those who had resulted in negative pregnancy test (LEI-NP group, n = 114). The female age, basal follicle stimulating hormone concentration, number of past oocyte pickup cycles, and embryos/blastocysts transferred in the past three RIF cycles were significantly (p < 0.047) lower in the LEI-CP group than the LEI-NP group. The prevalence of polycystic ovarian syndrome was significantly (p = 0.0059) higher in the LEI-CP group than in the LEI-NP group. These findings suggest that LEI is most effective to improve the pregnancy outcome in patients undergoing RIF with uncompromised ovarian reserve, particularly in those with polycystic ovarian syndrome.

Chronic Endometritis: Potential Cause of Infertility and Obstetric and Neonatal Complications.

Chronic endometritis (CE) is a local inflammatory disease characterized by unusual plasmacyte infiltration in the endometrial stromal areas. CE has been neglected in gynecologic practice, as it is a less symptomatic benign disease that requires demanding and time-consuming histopathologic examinations for the definite diagnosis. Recent studies, however, suggest the association of CE with infertility and obstetric and neonatal complications. In this review article, we aimed to update the knowledge on epidemiology, etiology, and pathogenesis of CE as well as discuss its clinical management from diagnosis to treatment.

Expression of apoptosis in placenta of experimental antiphospholipid syndrome mouse.

PROBLEM: To study the histopathology and expression of apoptosis in placenta of pregnancy-complicated antiphospholipid syndrome (APS)-positive mouse models. METHOD OF STUDY: ICR mice were immunized with IgG isotype of human anticardiolipin (aCL) and/or lupus anticoagulant (LA). The pathological and apoptotic expression was studied in the placenta of positive APS mice and compared with respective control samples. RESULTS: Mice with passive immunization of human aCL and/or LA produced an increase in fetal resorption along with markedly induced thrombosis in the placenta associated with increased placental apoptosis. In addition, fewer mitotic cells, less trophoblast giant cell invasion, and more shrunken cells in the deciduas were seen. CONCLUSION: Our study showed the pathogenic role of aCL and LA in pregnancy complications.

A unique preliminary study on placental apoptosis in mice with passive immunization of anti-phosphatidylethanolamine antibodies and anti-factor XII antibodies.

PROBLEM: Antiphospholipid antibodies have been investigated both in humans and in animal models. In contrast, there are fewer reports describing anti-phosphatidylethanolamine (aPE) antibodies in humans, and there are no reports of animal studies with aPE till date. Clinically, FXII deficiency or anti-FXII antibodies are sometimes associated with aPE in patients with recurrent pregnancy loss. Therefore, we asked whether aPE and/or anti-FXII in mice could cause fetal resorption, placental thrombosis and apoptosis. Moreover, antibodies to respective target antigens (LDC27 or IPP30) could cause pregnancy failure as well. METHODS OF STUDY: Animal models were used to carry out these objectives. All the animals were immunized with different antibodies by passive immunization. Placental samples were used for various observations. RESULTS AND CONCLUSIONS: Mice with passive immunization of aPE (or anti-LDC27) and aFXII (or anti-IPP30) produced a slight increase in fetal resorption, but markedly induced thrombosis and hemorrhage in the placenta associated with lower platelet counts and increased placental apoptosis. In addition, fewer mitotic cells, less trophoblast giant cell invasion, and more shrunken cells in the deciduas were seen. Our study supports the pathogenic role of aPE and aFXII in pregnancy complications and also suggests a beneficial role of LDC27 and IPP30 antigens on pregnancy failures.

Relevance of the site of assisted hatching in thawed human blastocysts: a preliminary report.

Preliminary data from a prospective randomized study of assisted hatching (AH) of thawed human blastocysts demonstrated that the rate of complete hatching was significantly higher for AH performed near the inner cell mass (ICM) than for AH at the side opposite to the ICM. This suggests the existence of polarity in the hatching process in human blastocysts, which requires further evaluation.

Autoantibodies and coagulation in reproductive medicine.

Management of recurrent pregnancy loss (RPL) is considered to be difficult, in part because of cunfusion between autoantibodies and coagulation disorders. Autoantibodies and coagulation are related; two groups of multicenter studies concerning autoantibodies and coagulation reported that factor XII deficiency, hypofibrinolysis, anti-phosphatidylethanolamine (aPE), anti-beta2-glycoprotein I, anti-annexin A5, and lupus anticoagulant (LA) were found to be frequent risk factors in RPL women. Therefore, discrimination of autoantibodies and coagulation is important in understanding RPL well. We propose three types of pathways regarding reproduction, which are different and independent: (1) Negatively charged-phospholipid related antibodies (anti-phosphatidylserine; aPS, anti-cardiolipin; aCL, lupus anticoagulant; LA, anti-annexin A5; aANX), (2) factor XII-aPE-fibrinolysis: suppression of fibrinolysis, (3) protein C-protein S-factor V: loss of inactivation against activated factor V. Women with RPL and infertility showed similar findings in terms of the above clinical tests. Available data, however, is not enough to conclude whether these are pathogenic to infertile women.

Decreased factor XII activity is associated with recurrent IVF-ET failure.

PROBLEM: A decrease in factor XII (FXII) activity has been observed in women with unexplained recurrent miscarriages. Because of the many similarities between recurrent in vitro fertilization-embryo transfer (IVF-ET) failure and early pregnancy loss patients, we investigated whether women with recurrent IVF-ET failure had low FXII activity. METHOD OF STUDY: Blood from 110 patients with three or more IVF-ET failures was tested for FXII activity, autoantibodies and other coagulation parameters. These patients were compared with 191 recurrent miscarriage patients, 87 controls. FXII activity was measured by an activated partial thromboplastin time (APTT) assay. RESULTS: Factor XII activity of the IVF-ET failure group (median 79.5, range 37-150) was significantly lower than that of control group (median 109, range 35-225, P < 0.001 by Mann-Whitney test) or that of recurrent pregnancy loss (RPL) group (median 92, range 20-205). The FXII activity of IVF-ET failure patients was positively correlated with age, but not associated with the number of IVF-ET failures, infertile duration, autoantibodies, or other coagulation parameters. CONCLUSION: Decreased FXII activity may causally relate to reproductive failure.