The association between SARS-CoV-2 infection and late pregnancy loss

COVID-19 infection during pregnancy and risk of early and late spontaneous miscarriages: A matched case-control population-based study

OBJECTIVES

To evaluate the effect of COVID-19 during the first trimester on the rate of first- and second-trimester miscarriages. Secondary aims include the effect on stillbirths and the correlation between symptom severity and pregnancy outcomes.

METHODS

A retrospective matched case-control population-based study extracted data from electronic medical records of a nationwide database of the second largest healthcare organization that provides medical services to over 2 000 000 patients in Israel. Pregnancy outcomes in COVID-19-positive pregnant patients in 2020 were compared with an age- and gestational-week-matched 1:2 case-control cohort of pre-pandemic pregnant patients that received medical care in 2019.

RESULTS

Of 68 485 pregnant women treated in 2020, 2333 were COVID-19-positive during pregnancy: 215 during the first trimester, 791 during the second trimester, and 1327 during the third trimester. We compared these data with the control cohort of 4580 pre-pandemic pregnant patients. The rate of spontaneous miscarriage was significantly higher 146/2187 (6.3%) in COVID-19-positive patients versus 214/4580 (4.7%), (P < 0.01, odds ratio 1.34, 95% confidence interval 1.094-1.691). Most miscarriages occurred during the first trimester in both groups, yet the rates were significantly higher in the study group (5.4% vs 3.8%, P < 0.01). There was no association between COVID-19 severity and miscarriage risk.

CONCLUSION

COVID-19 diagnosis during early pregnancy increased the rate of spontaneous miscarriage in our cohort compared with an age- and gestational-week-matched pre-pandemic control group.

Placental SARS-CoV-2 Infection and Its Implications for Increased Risk of Adverse Pregnancy Outcomes

OBJECTIVE

 Pregnant women are at increased risk of coronavirus disease 2019 (COVID-19). This could be explained through the prism of physiologic and immunologic changes in pregnancy. In addition, certain immunological reactions originate in the placenta in response to viral infections.This study aimed to investigate whether severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) can infect the human placenta and discuss its implications in the pathogenesis of adverse pregnancy outcomes.

STUDY DESIGN

 We conducted a retrospective cohort study in which we collected placental specimens from pregnant women who had a laboratory-confirmed SARS-CoV-2 infection. We performed RNA in situ hybridization assay on formalin-fixed paraffin-embedded tissues to establish the in vivo evidence for placental infectivity by this corona virus. In addition, we infected trophoblast isolated from uninfected term human placenta with SARS-CoV-2 variants to further provide in vitro evidence for such an infectivity.

RESULTS

 There was a total of 21 cases enrolled, which included 5 cases of spontaneous preterm birth (SPTB) and 2 intrauterine fetal demises (IUFDs). Positive staining of positive-sense strand of SARS-CoV-2 virions was detected in 15 placentas including 4 SPTB and both IUFDs. In vitro infection assay demonstrated that SARS-CoV-2 virions were highly capable of infecting both cytotrophoblast and syncytiotrophoblast.

CONCLUSION

 This study implies that placental SARS-CoV-2 infection may be associated with an increased risk of adverse obstetrical outcomes.

KEY POINTS

· SARS-CoV-2 can effectively infect human placenta.. · Such infectivity is confirmed by in vitro experiments.. · Placental SARS-CoV-2 corelates with adverse obstetrical outcomes..

SARS-CoV-2 infection induces activation of ferroptosis in human placenta

Ferroptosis, a regulated non-apoptotic form of cell death, has been implicated in the response to varied types of infectious agents including virus. In this study, we sought to determine whether SARS-CoV-2 infection can induce activation of ferroptosis in the human placenta. We collected placentas from 23 pregnant females with laboratory-confirmed SARS-CoV-2 following delivery and then used RNA in situ hybridization assay for detection of viral positive-sense strand (PSS) to confirm that these placentas have been infected. We also used immunohistochemistry assay to assess expression levels of acyl-CoA synthetase long-chain family member 4 (ACSL4), an essential executioner of ferroptosis in the same specimens. Our results showed that ACSL4 expression was significantly increased in the group with positive positive-sense strand staining compared to their negative counterparts (p = 0.00022). Furthermore, we found that there was a positive trend for increased PSS staining along with increased ACSL4 expression. Our study supports that ferroptosis is activated in the response to SARS-CoV-2 infection in the human placenta, highlighting a molecular mechanism potentially linking this coronavirus infection and pathogenesis of adverse pregnancy outcomes.

The impact of past COVID-19 infection on pregnancy rates in frozen embryo transfer cycles

PURPOSE

To study the effect of SARS-CoV-2 infection on pregnancy rates in frozen embryo transfer (FET) cycles.

METHODS

A retrospective cohort study including women under the age of 42 with documented SARS-CoV-2 infection up to 1 year prior to treatment, undergoing FET cycles in the first half of 2021, with transfer of embryos generated prior to the infection. Controls were SARS-CoV-2 non-diagnosed, non-vaccinated women matched by age, number, and day of embryo transfer. Demographic and cycle characteristics and outcomes were compared.

RESULTS

Forty-one recovered women and 41 controls were included. Pregnancy rates were 29% and 49% respectively (p = 0.070). Stratification by time from SARS-CoV-2 infection to transfer into ≤ 60 and > 60 days revealed a difference in pregnancy rates, with women in the COVID group having lower pregnancy rates if infected in proximity to the transfer (21% vs. 55%; p = 0.006). In a logistic regression model, infection was a significant variable (p = 0.05, OR 0.325, 95% CI 0.106-0.998). Logistic regression applied on the subgroup of women infected in proximity to the transfer further strengthened the univariate results, with COVID-19 remaining a significant parameter (p = 0.005, OR 0.072, 95% CI 0.012-0.450).

CONCLUSIONS

In FET cycles of patients with past SARS-CoV-2 infection, in which oocytes were retrieved prior to infection, decreased pregnancy rates were observed, specifically in patients who recovered less than 60 days prior to embryo transfer. Pending further studies, in cases of FET cycles with limited number of embryos, postponing embryo transfer for at least 60 days following recovery from COVID-19 might be considered when feasible.