Recurrent second trimester pregnancy loss: evaluation and management

Subsequent pregnancy outcomes after second trimester miscarriage or termination for medical/fetal reason: A systematic review and meta-analysis of observational studies

INTRODUCTION

Women with a prior stillbirth or a history of recurrent first trimester miscarriages are at increased risk of adverse pregnancy outcomes. However, little is known about the impact of a second trimester pregnancy loss on subsequent pregnancy outcome. This review investigated if second trimester miscarriage or termination for medical reason or fetal anomaly (TFMR/TOPFA) is associated with future adverse pregnancy outcomes.

MATERIAL AND METHODS

A systematic review of observational studies was conducted. Eligible studies included women with a history of a second trimester miscarriage or termination for medical reasons and their pregnancy outcomes in the subsequent pregnancy. Where comparative studies were identified, studies which compared subsequent pregnancy outcomes for women with and without a history of second trimester loss or TFMR/TOPFA were included. The primary outcome was livebirth, and secondary outcomes included: miscarriage (first and second trimester), termination of pregnancy, fetal growth restriction, cesarean section, preterm birth, pre-eclampsia, antepartum hemorrhage, stillbirth and neonatal death. Studies were excluded if exposure was nonmedical termination or if related to twins or higher multiple pregnancies. Electronic searches were conducted using the online databases (MEDLINE, Embase, PubMed and The Cochrane Library) and searches were last updated on June 16, 2023. Risk of bias was assessed using the Newcastle-Ottawa scale. Where possible, meta-analysis was undertaken. PROSPERO registration: CRD42023375033.

RESULTS

Ten studies were included, reporting on 12 004 subsequent pregnancies after a second trimester pregnancy miscarriage. No studies were found on outcomes after second trimester TFMR/TOPFA. Overall, available data were of "very low quality" using GRADE assessment. Meta-analysis of cohort studies generated estimated outcome frequencies for women with a previous second trimester loss as follows: live birth 81% (95% CI: 64-94), miscarriage 15% (95% CI: 4-30, preterm birth 13% [95% CI: 6-23]).The pooled odds ratio for preterm birth in subsequent pregnancy after second trimester loss in case-control studies was OR 4.52 (95% CI: 3.03-6.74).

CONCLUSIONS

Very low certainty evidence suggests there may be an increased risk of preterm birth in a subsequent pregnancy after a late miscarriage. However, evidence is limited. Larger, higher quality cohort studies are needed to investigate this potential association.

Clinical presentation, investigation, underlying causes, and subsequent pregnancy outcomes among different phenotypes of second trimester miscarriage

AIM

To evaluate the causes of miscarriage and subsequent pregnancy outcomes among different phenotypes of second trimester miscarriage.

METHODS

Retrospective analysis of 170 consecutive second trimester miscarriages between 14 + 0 and 23 + 6 weeks recorded in the Clinical Data Analysis and Reporting System from 2012 to 2021. Cases were excluded if miscarriages occurred before 14 + 0 weeks of gestation, data were incomplete, or passage of the fetus happened before the clinical assessment. Cases were classified with a stepwise approach into three phenotypic groups including silent miscarriages (ST-SM), rupture of membranes (ST-ROM), and inevitable miscarriages (ST-IM) depending on the fetal heart pulsation and leakage of liquor at presentation. Clinical investigation of the underlying causes and the outcome of the subsequent pregnancy was then reviewed.

RESULTS

There were 97 cases of ST-SM, 21 cases of ST-ROM, and 52 cases of ST-IM. Placental histology and karyotype examination were more likely to yield significant results in the cases of ST-ROM and ST-SM (p < 0.05). The phenotypic examination identified different underlying causes including fetal anomaly, suspected cervical insufficiency, diabetes mellitus, and unknown causes (p < 0.001). Sixty-four cases achieved a subsequent pregnancy. Although women with history of ST-ROM and ST-IM received more cervical length monitoring and cervical cerclage than those with ST-SM (66.7% vs. 44.4% vs. 7.5%, p = 0.0002; and 16.7% vs. 22.2% vs. 2.5%, p = 0.031, respectively), the risk of recurrent second trimester miscarriage was higher in ST-ROM and ST-IM than in ST-SM (16.7% vs. 0%, p = 0.018).

CONCLUSION

The classification can differentiate different second trimester miscarriage phenotypes, which offers essential information to guide investigation panels of the underlying cause of miscarriages, and the prognosis and management of subsequent pregnancy. Future researches focused on second trimester miscarriage should report their findings according to different phenotypes.

ZBTB24 (Zinc Finger and BTB Domain Containing 24) prevents recurrent spontaneous abortion by promoting trophoblast proliferation, differentiation and migration

Recurrent spontaneous abortion (RSA) is a common complication during early gestation, which is associated with aberrant DNA methylation. Zinc Finger and BTB Domain Containing 24 (ZBTB24) plays a critical role in facilitating DNA methylation and cell proliferation. However, the regulatory role of ZBTB24 on trophoblast development in RSA remains unclear. In this study, ZBTB24 expression was compared between decidua tissues of RSA patients and induced abortion controls from a published dataset, which was further validated in placental villi tissues by RT-qPCR and Western blot. The roles of ZBTB24 in trophoblast proliferation, differentiation, and migration were investigated by functional assays after ZBTB24 knockdown or overexpression in HTR-8/SVneo cells. Our results showed that ZBTB24 expression was significantly decreased in RSA patients, and ZBTB24 expression level positively regulated cell viability, differentiation, and migration in HTR-8/SVneo cells. We further demonstrated that ZBTB24 modulated the expression of E-cadherin by altering the DNA methylation at the promoter region. Overall, the downregulation of ZBTB24 is implicated in RSA by inhibiting trophoblast proliferation, differentiation, and migration. Therefore, ZBTB24 may serve as a promising therapeutic target and diagnostic marker for RSA.

Long Non-Coding RNA ZEB2-AS1 Augments Activity of Trophoblast Cells and Prevents the Development of Recurrent Spontaneous Abortion in Mice Through EZH2-Mediated CST3 Inhibition

Recurrent spontaneous abortion (RSA) is the most common complication of pregnancy where reduced invasion of trophoblasts plays a major role. This work aimed to explore the effect of abnormally expressed long non-coding RNA (lncRNA) ZEB2-AS1 on the occurrence of RSA. Differentially expressed lncRNAs in trophoblast cells between healthy controls and patients with RSA were screened using the GEO database. Female CBA/J mice were allowed to mate with male DBA/2 mice to establish inbred mice with RSA. ZEB2-AS1 was poorly expressed in placental tissues and trophoblast cells in the condition of RSA. ZEB2-AS1 upregulation augmented proliferation, migration, and invasion of trophoblast cells in vitro. ZEB2-AS1 negatively regulated cystatin C (CST3) expression. Further overexpression of CST3 blocked the activity of trophoblast cells. ZEB2-AS1 recruited enhancer of EZH2 to the promoter region of CST3, which increased H3K27me3 modification to suppress CST3 expression. In vivo, overexpression of ZEB2-AS1 reduced embryo resorption rate and increased the weights of fetuses and placentas in mice with RSA. However, the protective roles of ZEB2-AS1 were blocked upon artificial silencing of EZH2 or upregulation of CST3. Taken together, this study demonstrates that ZEB2-AS1 enhances activity of trophoblast cells and prevents RSA development through reducing CST3 expression in an EZH2-dependent manner.

MiR-103 protects from recurrent spontaneous abortion via inhibiting STAT1 mediated M1 macrophage polarization

Recurrent spontaneous abortion (RSA) is a common complication of early pregnancy. Excessive M1 macrophage was found to be involved in RSA, but the underlying mechanisms remains unclear. MicroRNAs play critical roles in RSA as well as the polarization of macrophages; however, the regulatory effect of miRNAs on M1 differentiation in RSA has not been fully investigated. In this study, miRNA microarray assay revealed that miR-103 was significantly decreased in RAW264.7-derived M1 macrophages upon IFNγ and LPS stimulation. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis showed that in RSA patients, miR-103 expression was decreased substantially, and negatively correlated with that of STAT1. Moreover, down-regulation of miR-103 could sensitively discriminate RSA patients from normal pregnancies (NP) subjects. Experiments in vitro showed that overexpression of miR-103 suppressed M1 polarization by inhibiting STAT1/IRF1 signaling pathway and vice versa. miR-103 regulated STAT1 expression by direct binding to its 3'-UTR. Moreover, our in vivo study demonstrated that overexpressed miR-103 could reduce mice embryo resorption and M1 polarization effectively. Overall, the results suggested that decreased miR-103 was involved in RSA by increasing M1 macrophage polarization via promoting STAT1/IRF1 signaling pathway. miR-103 may be explored as a promising diagnostic marker and therapeutic target for RSA.

Early Pregnancy Losses: Review of Nomenclature, Histopathology, and Possible Etiologies

Miscarriage is a frequent complication of human pregnancy: ∼50% to 70% of spontaneous conceptions are lost prior to the second trimester. Etiology of miscarriage includes genetic abnormalities, infections, immunological and implantation disorders, uterine and endocrine abnormalities, and lifestyle factors. Given such variability, knowledge regarding causes, pathophysiological mechanisms, and morphologies of primary early pregnancy loss has significant gaps; often, pregnancy losses remain unexplained. Pathologic evaluation of miscarriage tissue is an untapped source of knowledge. Although miscarriage specimens comprise a significant part of pathologists' workload, information reported from these specimens is typically of minimal clinical utility for delineating etiology or predicting recurrence risk. Standardized terminology is available, though not universally used. We reintroduce the terminology and review new information about early pregnancy losses and their morphologies. Current clinical terminology is inconsistent, hampering research progress. This review is a resource for diagnostic pathologists studying this complex problem.

Recurrence of second trimester miscarriage and extreme preterm delivery at 16-27 weeks of gestation with a focus on cervical insufficiency and prophylactic cerclage

INTRODUCTION

The objective of this study was to describe recurrence rates of second trimester miscarriage and extreme preterm delivery by phenotype and use of prophylactic cerclage in a register-based cohort.

MATERIAL AND METHODS

We included women with a first second trimester miscarriage or extreme preterm delivery (16⁺⁰ to 27⁺⁶ gestational weeks) in Denmark in 1997-2012 (n = 9602) by combined use of the Danish Medical Birth Register and the Danish National Patient Register. Eight phenotypes were identified by ICD-10 codes in a hierarchy with the following sequence: major fetal anomaly, multiple gestation, uterine anomaly, placental insufficiency, antepartum bleeding, cervical insufficiency, preterm premature rupture of membranes, and intrauterine fetal death. Recurrence rate after a second trimester miscarriage/spontaneous delivery in the period was calculated based on the register data. In cervical insufficiency outcome was stratified by prophylactic cerclage applied <16 weeks of gestation.

RESULTS

Overall recurrence rate was 7.3% (n = 452), a rate that differed by phenotype from <5% (fetal anomaly, multiple gestations, intrauterine fetal death) to 21% (cervical insufficiency). In women with cervical insufficiency the recurrence rate was 28% without cerclage; vaginal cerclage was associated with a significant reduction [adjusted odds ratio (OR) 0.47; 95% CI 0.29-0.76] and abdominal cerclage with an even greater reduction (adjusted OR 0.14; 95% CI 0.03-0.61).

CONCLUSIONS

The overall recurrence rate of second trimester miscarriage or extreme preterm delivery was 7%, but it differed significantly by phenotype. The highest rate, 28%, was found in cervical insufficiency, and prophylactic cerclage was associated with a significant reduction in recurrence.

Validation of second trimester miscarriages and spontaneous deliveries

Objective

To validate the diagnosis of second trimester miscarriages/deliveries (16+0 weeks to 27+6 weeks of gestation) recorded as miscarriages in the Danish National Patient Registry or spontaneous deliveries in the Danish Medical Birth Registry, and asses the validity of risk factors, pregnancy complications, and cerclage by review of medical records.

Materials and methods

In a cohort of 2,358 women with a second trimester miscarriage/delivery in first pregnancy and a subsequent delivery during 1997–2012, we reviewed a representative sample of 682 medical records. We searched for clinically important information and calculated positive predictive values of the registry diagnoses stratified by type of registry, as well as sensitivity, specificity, positive predictive value, and kappa coefficients of risk factors, pregnancy complications, and cerclage.

Results

Miscarriage/spontaneous delivery in the second trimester was confirmed in 621/682 patients (91.1%). Pregnancy complications in second trimester miscarriages were underreported, resulting in low sensitivities and poor to moderate agreements between records and registries. There was a good agreement (kappa >0.6) between medical records and the registries regarding risk factors and cerclage. The diagnosis of cervical insufficiency had “moderate” kappa values for both miscarriages and deliveries (0.55 and 0.57).

Conclusion

Spontaneous second trimester deliveries and miscarriages recorded in the registers were confirmed by medical records in 91%, but register-based information on pregnancy complications need to be improved. We recommend that all pregnancies ending spontaneously beyond the first trimester are included in the national birth registry and described by appropriate variables.

Radiographic evaluation of stillbirth: what does it contribute?

Despite advances in perinatal care, stillbirth is relatively common (1/160 births) and frequently remains unexplained. Most recent protocols for etiologic evaluation of stillbirth either omit radiography or reserve it for infants with obvious skeletal disproportion. Over the past 30 years, the Wisconsin Stillbirth Service Program has collected radiographic images from 2,032 stillbirths and second trimester losses, of which about 25% (517) showed abnormalities. Review of these images by a medical geneticist showed that radiographs yielded a diagnosis in 45% of the infants with abnormalities (11.5% of all radiographs obtained) and were critical, yielding a diagnosis that would otherwise have been missed or incomplete in 1.5% of the total infants. The probability of a diagnosis was not significantly different between miscarriages <20 weeks and stillbirths. Diagnoses were mainly fetal, most commonly sporadic birth defects, idiopathic hydrops, chromosome abnormalities, and skeletal dysplasias, but chorioamnionitis with fetal sepsis, complications of twinning, and cord accidents were also diagnosed radiographically. Radiographs may help direct the use of newer technologies such as chromosomal microarray or gene sequencing. Limiting radiographs to infants with obvious skeletal disproportion would have resulted in many of these diagnoses, including 4/24 skeletal dysplasias, being overlooked. We recommend at least an anterior/posterior babygram film as part of the permanent record of all second trimester losses and stillbirths.

Stillbirth: the heart of the matter

We evaluated 2,083 cases within the Wisconsin Stillbirth Service Program (WiSSP) that had autopsy reports or ultrasound data relevant to the heart. Of these, 167/1,782 (9.4%) stillbirths after 20 weeks and 11/301 (3.7%) miscarriages <20 weeks had congenital heart disease (CHD). Cases were classified by type of heart defect and whether it related to cause of death. Among cardiac anomalies that contributed significantly to fetal death, 125/151 (83%) were associated with underlying conditions or syndromes, nearly half of which were chromosomal. The most common forms of CHD in stillborns were severe cyanotic lesions (3%), then ventricular (2.6%) and atrial (1.9%) septal defects. Compared to livebirths, this represents a shift toward more severe cardiac lesions, although all comparable categories, including non-lethal conditions such as atrial septal defect, are more common in stillbirths. Clinical cardiomyopathy was identified as cause of death in 1.2% of stillborns. Cardiomegaly, occurring in 26.7% of all cases and 76.7% of infants born to diabetic mothers, may represent undiagnosed cardiomyopathy and/or may decrease fetal tolerance of hypoxia. In contrast, 78.5% of Turner syndrome infants, all <32 weeks, had small hearts. More attention to cardiac findings can lead to increased understanding of stillbirth causes. Based on our findings, we recommend chromosome studies on all stillbirths and close attention to the heart during second trimester ultrasounds, with chromosome studies offered if CHD is found. Consideration of heart size can result in prenatal identification of infants at risk for stillbirth, particularly large hearts in fetuses of diabetic mothers in the third trimester, which may identify fetal cardiomyopathy before it becomes life-threatening.

Mid-trimester pregnancy loss

Mid-trimester pregnancy loss (MTL) occurs between 12 and 24 weeks' gestation. The true incidence of this pregnancy complication is unknown, because research into MTL in isolation is scarce, although the estimated incidence has been noted to be 2% to 3% of pregnancies. A comprehensive preconceptual screening protocol is recommended, because the cause for an MTL may be present in isolation or combined (dual pathology), and is often heterogeneous. Patients with a history of MTL are at an increased risk of future miscarriage and preterm delivery. This risk is increased further depending on the number of associative factors diagnosed.

Intrauterine fetal demise can be remote from the inciting insult in an animal model of hypoxia-ischemia

BACKGROUND

Fetal hypoxia-ischemia (H-I) results in significant morbidity and mortality. Little is known about the timing of death in human stillbirths. The vulnerability of the fetus varies with age at the time of insult, but it is unknown what happens to the timing of fetal death in relation to a fetal insult. We asked the question of whether the timing of fetal death was influenced by the age at which the insult occurred.

METHODS

Fetal H-I was achieved at three ages by sustained uterine ischemia in rabbits, mimicking the acute placental insufficiency of placental abruption.

RESULTS

H-I at 22 d gestation (E22) resulted in fewer perinatal deaths than at E25 and E29. Fetal deaths were grouped into early and late perinatal deaths. Early perinatal death mostly occurred immediately after H-I and these fetuses delivered before term. Late perinatal death occurred between the insult and delivery at term gestation. Early perinatal death occurred more often in the E25 hypoxic-ischemic group as compared with those of the E22 hypoxic-ischemic group.

CONCLUSION

There is an increasing vulnerability to hypoxia with increasing gestational age. Perinatal deaths may occur long after the episode of H-I. The timing of an intrauterine hypoxic-ischemic event cannot be inferred from the detection of fetal death.

Wisconsin stillbirth services program: a multifocal approach to stillbirth analysis

Stillbirth accounts for about 26,000 deaths annually in the US. In most previous studies, discrete causes are identified in less than half of all stillbirths. In order to identify causes and non-causal but potentially contributing abnormalities, we analyzed 416 of the most recent (2004-2010) Wisconsin Stillbirth Service Program (WiSSP) cases from a multifocal approach. In 70% of cases a cause sufficient to independently explain the demise was identified including 40% placental, 21.5% fetal, and 12.7% maternal. Results for stillbirths and second trimester miscarriages did not differ significantly. In 95% of cases at least one cause or non-causal abnormality was recognizable, and in two-thirds of cases, more than one cause or non-causal abnormality was identified. In cases with maternal cause, the placenta was virtually always abnormal. Both placentas (59%) and fetuses (38%) were frequently smaller than expected for gestational age. Previous miscarriage and/or stillbirth were risk factors for second and third trimester losses, with 35% of previous pregnancies ending in fetal demise. Recommendations include complete evaluation of all second and third trimester losses with special attention to placental pathology and thorough investigation for multiple causes or abnormalities whether or not a primary cause is initially recognized. Improved understanding of the causes of late miscarriage and stillbirth may contribute to recognition and management of pregnancies at risk and eventually to prevention of stillbirth.