The possible role of intrauterine infections in unexplained second trimester abortions and macerated stillbirths: a study from a single center

Vertical transmission potential of SARS-CoV-2 from infected mother to twin neonates

Background: Limited details are available regarding the vertical transmission potential of COVID-19 infection in pregnant women. The authors' current study aimed to report the vertical transmission potential of COVID-19 infection in a woman pregnant with twins. Case description: The authors report the case of a 27-year-old woman infected with SARS-CoV-2. The patient was pregnant with dichorionic diamniotic fraternal twins and admitted to Renmin Hospital of Wuhan University, Wuhan, China. After undergoing a cesarean section, the patient gave birth to premature twins, who tested positive for COVID-19 infection. Interpretation: Findings from this case suggest a possibility of intrauterine infection caused by vertical transmission in a woman infected with COVID-19.

No. 394-Stillbirth Investigation

OBJECTIVES

To provide an investigation protocol to help health care providers determine the cause of a fetal death.

OPTIONS

Consideration has been given to protocols for the investigation of fetal death that are currently available in Canada and in other countries.

OUTCOMES

Identification of possible causes of stillbirth and their relationship to future pregnancies.

EVIDENCE

Articles related to the etiology of fetal death were identified in a search of PubMed (June 2006 to September 2018), the Cochrane Library, and investigation protocols from the American College of Obstetricians and Gynecologists, the International Stillbirth Alliance Collaborative for Improving Classification of Perinatal Deaths, the Royal College of Obstetricians and Gynaecologists, the Queensland clinical guidelines, and the Reproductive Care Program of Nova Scotia.

BENEFITS

To provide better advice for women regarding possible causes of fetal death and implications for future pregnancies.

VALIDATION

The evidence obtained was reviewed and evaluated by the Maternal-Fetal Medicine Committee and the Clinical Practice Obstetrics Committee of the Society of Obstetricians and Gynaecologists of Canada. The level of evidence and quality of the recommendation made was described using the Evaluation of Evidence criteria of the Canadian Task Force on Preventive Health Care.

RECOMMENDATIONS

Body size and risk of spontaneous abortion among danish pregnancy planners

BACKGROUND

Several studies indicate that female obesity increases the risk of spontaneous abortion (SAB). Central adiposity, height, and location of typical weight gain have not been examined as risk factors for SAB.

METHODS

We examined the associations between selected anthropometric factors and risk of SAB among 5132 women enrolled in a Danish Internet-based prospective cohort study of pregnancy planners. We used Cox proportional hazards regression models, with gestational weeks as the time scale, to compute hazard ratios (HRs) of SAB and 95% confidence intervals (CIs).

RESULTS

After adjustment for potential confounders, the HRs for SAB among underweight (body mass index (BMI, kg/m(2) ) <20), overweight (BMI: 25-29) and obese (BMI ≥30) women were 1.00 [95% CI: 0.81, 1.24], 0.90 [95% CI: 0.73, 1.09] and 1.23 [95% CI: 0.98, 1.54], respectively, compared with normal weight women (BMI 20-24). The association between obesity and SAB was stronger for early SAB (<8 weeks gestation); HR: 1.34 95% CI: 1.01, 1.77. The HR for height ≥174 cm vs. <166 cm was 0.81 [95% CI: 0.66, 1.00]. Increased waist-to-hip ratio (WHR) was inversely associated with risk of SAB (HR: 0.81; 95% CI: 0.63, 1.05). Waist circumference and location of typical weight gain were not appreciably associated with SAB risk.

CONCLUSIONS

This study confirms previous studies that have shown a small positive association between obesity and SAB risk. Our results suggest that obesity is a stronger risk factor for early pregnancy losses, and that small stature and low WHR are associated with an increased risk of SAB.

Genetic diversity of the HLA-G coding region in Amerindian populations from the Brazilian Amazon: a possible role of natural selection

HLA-G has an important role in the modulation of the maternal immune system during pregnancy, and evidence that balancing selection acts in the promoter and 3'UTR regions has been previously reported. To determine whether selection acts on the HLA-G coding region in the Amazon Rainforest, exons 2, 3 and 4 were analyzed in a sample of 142 Amerindians from nine villages of five isolated tribes that inhabit the Central Amazon. Six previously described single-nucleotide polymorphisms (SNPs) were identified and the Expectation-Maximization (EM) and PHASE algorithms were used to computationally reconstruct SNP haplotypes (HLA-G alleles). A new HLA-G allele, which originated in Amerindian populations by a crossing-over event between two widespread HLA-G alleles, was identified in 18 individuals. Neutrality tests evidenced that natural selection has a complex part in the HLA-G coding region. Although balancing selection is the type of selection that shapes variability at a local level (Native American populations), we have also shown that purifying selection may occur on a worldwide scale. Moreover, the balancing selection does not seem to act on the coding region as strongly as it acts on the flanking regulatory regions, and such coding signature may actually reflect a hitchhiking effect.

Infection and fetal loss in the mid-second trimester of pregnancy

INTRODUCTION

Chorioamnionitis is a common cause of second trimester pregnancy loss, usually due to ascending infection. This study investigates the prevalence and bacteriology of chorioamnionitis in cases of spontaneous pregnancy loss in previable gestations (16-22 weeks).

METHODS

Fetal losses between 16- and 22-week gestation were identified from the institutional database over a three-year period. Cases with an autopsy were identified, pathology reports reviewed, and maternal features noted (clinical symptoms, blood count and vaginal culture results). Second trimester medical termination for fetal abnormality during the same time period served as controls for the confounding influence of labour.

RESULTS

A total of 101 cases of spontaneous non-anomalous non-macerated fetal losses and 103 control cases of induced loss for fetal anomaly were identified. Median gestation of cases was 19 weeks (interquartile range (IQR) 17, 21) and of controls was 20 weeks (IQR 19, 21). Maternal white cell count was higher in cases (median 13.6 IQR 10.8, 16.6) than in controls (9.9 IQR 7.6, 11.5) (P < 0.01). Seventy-eight (77.2%) of 101 cases and no controls had histological chorioamnionitis. A fetal reaction was identified in 48.7% of cases with chorioamnionitis, and the frequency of fetal reaction increased as gestation advanced (5.3% at 16-week gestation vs 33.3% at 22-week gestation). In cases with chorioamnionitis 36/76 (47.4%) were culture positive, whereas 4/25 (16%) without chorioamnionitis were culture positive.

CONCLUSION

In otherwise normal fetuses, chorioamnionitis is a common finding in mid-trimester pregnancy loss. Routine culture methods have a low sensitivity for isolation of the causative micro-organisms. This inflammatory process seems to predate the onset of labour and appears a primary mechanism in the aetiology of such losses.

Viruses and other infections in stillbirth: what is the evidence and what should we be doing?

In Australia, as in other developed countries, approximately 40-50% of stillbirths are of unknown aetiology. Emerging evidence suggests stillbirths are often multifactorial. The absence of a known cause leads to uncertainty regarding the risk of recurrence, which can cause extreme anguish for parents that may manifest as guilt, anger or bewilderment. Further, clinical endeavours to prevent recurrences in future pregnancies are impaired by lack of a defined aetiology. Therefore, efforts to provide an aetiological diagnosis of stillbirth impact upon all aspects of care of the mother, and inform many parts of clinical decision making. Despite the magnitude of the problem, that is 7 stillbirths per 1000 births in Australia, diagnostic efforts to discover viral aetiologies are often minimal. Viruses and other difficult to culture organisms have been postulated as the aetiology of a number of obstetric and paediatric conditions of unknown cause, including stillbirth. Reasons forwarded for testing stillbirth cases for infectious agents are non-medical factors, including addressing all parents' need for diagnostic closure, identifying infectious agents as a sporadic cause of stillbirth to reassure parents and clinicians regarding risk for future pregnancies, and to reduce unnecessary testing. It is clear that viral agents including rubella, human cytomegalovirus (CMV), parvovirus B19, herpes simplex virus (HSV), lymphocytic choriomeningitis virus (LCMV), and varicella zoster virus (VZV) may cause intrauterine deaths. Evidence for many other agents is that minimal or asymptomatic infections also occur, so improved markers of adverse outcomes are needed. The role of other viruses and difficult-to-culture organisms in stillbirth is uncertain, and needs more research. However, testing stillborn babies for some viral agents remains a useful adjunct to histopathological and other examinations at autopsy. Modern molecular techniques such as multiplex PCR, allow searches for multiple agents. Now that such testing is available, it is important to assess the clinical usefulness of such testing.

Absence of the HLA-G*0105N allele in Amerindian populations from the Brazilian Amazon Region: a possible role of natural selection

The human leukocyte antigen G (HLA-G) null allele (G*0105N) is defined by a DeltaC deletion at exon 3. Its high frequency in populations from areas with high pathogen loads and the putative role of HLA-G in placental development suggest that the reduced G1 expression in G*0105N heterozygous placentas may improve the intrauterine defense against infections. The G*0105N allele frequencies were evaluated in 143 Amerindians from six isolated tribes that inhabit the Central Amazon to determine the existence of genotype frequencies that suggest balancing selection in favor of G*0105N heterozygotes. No copy of the null allele was found by exon 3 sequencing. Although this finding may be because of demographic or other selective factors, it also suggests no evidence of G*0105N heterozygous advantage.

HLA-G 14-bp polymorphism at exon 8 in Amerindian populations from the Brazilian Amazon

HLA-G (human leukocyte antigen-G) plays an important role in the modulation of the maternal immune system during pregnancy. HLA-G alleles presenting a 14-bp insertion at exon 8 have been associated with decreased messenger RNA levels, preeclampsia, and miscarriages. This suggests that natural selection may exert a strong influence against the insertion allele in isolated populations. DNA samples from 384 Amazonian Indians spread across seven isolated tribes were evaluated for the 14-bp polymorphism. The insertion frequency (38.54%) was somewhat low. The Ewens-Watterson's neutrality test showed a slight trend toward balancing selection operating at this locus but no correlation between the 14-bp locus and fertility data was found. To sum up, no definitive evidence was obtained indicating that the 14-bp frequencies in Amerindians depart from neutrality.