COVID-19 and miscarriage: From immunopathological mechanisms to actual clinical evidence.

The association between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the first half of pregnancy and pregnancy loss is still unknown. Infections by other coronaviruses, such as severe acute respiratory syndrome coronavirus (SARS-CoV) and the Middle East respiratory syndrome coronavirus (MERS-CoV), appear to increase the risk of miscarriage. The purpose of this study is to assess whether SARS-CoV-2 infection increases the risk of miscarriage. Firstly, a narrative review of the literature on animal and human studies was performed to analyze the immunopathological mechanisms of SARS-CoV-2 infection during preconception and early pregnancy, by which it may increase the risk of miscarriage. Secondly, a systematic review/meta-analysis of studies was conducted to assess the prevalence of miscarriage in COVID-19 patients diagnosed during pregnancy. Meta-analysis of proportions was used to combine data, and pooled proportions were reported. Seventeen case series and observational studies and 10 prevalence meta-analyses were selected for the review. The estimate of the overall miscarriage rate in pregnant women with COVID-19 was 15.3 % (95 % CI 10.94-20.59) and 23.1 (95 % CI 13.17-34.95) using fixed and random effect models, respectively. Based on the data in the current literature, the miscarriage rate (<22 weeks gestation) in women with SARS-CoV-2 infection is in the range of normal population. Well-designed studies are urgently needed to determine whether SARS-CoV-2 infection increases the risk of miscarriage during periconception and early pregnancy.

Maternal immune responses and obstetrical outcomes of pregnant women with COVID-19 and possible health risks of offspring.

Coronavirus disease 2019 (COVID-19) pandemic has spread rapidly across the world. The vast majority of patients with COVID-19 manifest mild to moderate symptoms but may progress to severe cases or even mortalities. Young adults of reproductive age are the most affected population by SARS-CoV-2 infection. However, there is no consensus yet if pregnancy contributes to the severity of COVID-19. Initial studies of pregnant women have found that COVID-19 significantly increases the risk of preterm birth, intrauterine growth restriction, and low birth weight, which have been associated with non-communicable diseases in offspring. Besides, maternal viral infections with or without vertical transmission have been allied with neurological and behavioral disorders of the offspring. In this review, obstetrical outcomes of women with COVID-19 and possible risks for their offspring are discussed by reviewing maternal immune responses to COVID-19 based on the current evidence. Structural and systemic follow-up of offspring who are exposed to SARS-CoV-2 in-utero is suggested.

Clinical molecular genetics evaluation in women with reproductive failures.

Molecular diagnostics is a rapidly growing branch of the clinical laboratory and has accelerated the advance of personalized medicine in the fields of pharmacogenomics, pharmacogenetics, and nutrigenomics. The versatility of molecular biology allows it to be effective in several medical fields that include reproduction, immunogenetics, and virology. Implementation of molecular and sequencing technology in reproductive medicine can add another layer of understanding to better define the causes behind infertility and recurrent reproductive loss. In the following, we examine current molecular methods for probing factors behind reproductive pregnancy loss including reverse transcription polymerase chain reaction and next generation sequencing (NGS). We review several current and potential genetic (DNA) and transcriptional (RNA)-based parameters in women with infertility that can be significant in diagnosis and treatment. These molecular factors can be inferred either from genomic DNA or RNA locally within the endometrium. Furthermore, we consider infection-based abnormalities such as human herpesvirus-6 and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Finally, we present future directions as well as data demonstrating the potential role of human endogenous retroviruses in pregnancy loss. We hope these discussions will assist the clinician in delineating some of the intricate molecular factors that can contribute to infertility and recurrent reproductive failures.

COVID-19 and immunomodulation treatment for women with reproductive failures.

COVID-19 pandemic is affecting various areas of health care, including human reproduction. Many women with reproductive failures, during the peri-implantation period and pregnancy, are on the immunotherapy using immune modulators and immunosuppressant due to underlying autoimmune diseases, cellular immune dysfunction, and rheumatic conditions. Many questions have been raised for women with immunotherapy during the COVID-19 pandemic, including infection susceptibility, how to manage women with an increased risk of and active COVID-19 infection. SARS-CoV-2 is a novel virus, and not enough information exists. Yet, we aim to review the data from previous coronavirus outbreaks and current COVID-19 and provide interim guidelines for immunotherapy in women with reproductive failures.

Why are pregnant women susceptible to COVID-19? An immunological viewpoint.

The 2019 novel coronavirus disease (COVID-19) was first detected in December 2019 and became epidemic in Wuhan, Hubei Province, China. COVID-19 has been rapidly spreading out in China and all over the world. The virus causing COVID-19, SARS-CoV-2 has been known to be genetically similar to severe acute respiratory syndrome coronavirus (SARS-CoV) but distinct from it. Clinical manifestation of COVID-19 can be characterized by mild upper respiratory tract infection, lower respiratory tract infection involving non-life threatening pneumonia, and life-threatening pneumonia with acute respiratory distress syndrome. It affects all age groups, including newborns, to the elders. Particularly, pregnant women may be more susceptible to COVID-19 since pregnant women, in general, are vulnerable to respiratory infection. In pregnant women with COVID-19, there is no evidence for vertical transmission of the virus, but an increased prevalence of preterm deliveries has been noticed. The COVID-19 may alter immune responses at the maternal-fetal interface, and affect the well-being of mothers and infants. In this review, we focused on the reason why pregnant women are more susceptible to COVID-19 and the potential maternal and fetal complications from an immunological viewpoint.