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Abstract：
Pregnant individuals infected with SARS-CoV-2 have higher rates of intensive care unit admission, oxygen requirement, need for mechanical ventilation, and death than nonpregnant individuals. Increased COVID-19 disease severity may be associated with an increased risk of viremia and placental infection. Maternal SARS-CoV-2 infection is also associated with pregnancy complications such as preeclampsia and preterm birth, which can be either placentally mediated or reflected in the placenta. Maternal viremia followed by placental infection may lead to maternal-fetal transmission (vertical), which affects 1% to 3% of exposed newborns. However, there is no agreed-upon or standard definition of placental infection. The National Institutes of Health/Eunice Kennedy Shriver National Institute of Child Health and Human Development convened a group of experts to propose a working definition of placental infection to inform ongoing studies of SARS-CoV-2 during pregnancy. Experts recommended that placental infection be defined using techniques that allow virus detection and localization in placental tissue by one or more of the following methods: in situ hybridization with antisense probe (detects replication) or a sense probe (detects viral messenger RNA) or immunohistochemistry to detect viral nucleocapsid or spike proteins. If the abovementioned methods are not possible, reverse transcription polymerase chain reaction detection or quantification of viral RNA in placental homogenates, or electron microscopy are alternative approaches. A graded classification for the likelihood of placental infection as definitive, probable, possible, and unlikely was proposed. Manuscripts reporting placental infection should describe the sampling method (location and number of samples collected), method of preservation of tissue, and detection technique. Recommendations were made for the handling of the placenta, examination, and sampling and the use of validated reagents and sample protocols (included as appendices).
摘要：
感染SARS-CoV-2的孕妇入院率较高,需氧量,需要机械通风，和死亡比没有怀孕的人。COVID-19疾病严重程度增加可能与病毒血症和胎盘感染的风险增加有关。产妇SARS-CoV-2感染也与妊娠并发症如先兆子痫和早产有关,可以通过胎盘介导或反映在胎盘中。产妇病毒血症后胎盘感染可能导致母婴传播（垂直），影响1%到3%的暴露新生儿。然而,胎盘感染没有商定或标准的定义.美国国立卫生研究院/EuniceKennedyShriver国家儿童健康与人类发展研究所召集了一组专家，提出了胎盘感染的工作定义，以告知正在进行的妊娠期间SARS-CoV-2的研究。专家建议使用允许通过以下一种或多种方法在胎盘组织中进行病毒检测和定位的技术来定义胎盘感染：与反义探针（检测复制）或有义探针（检测病毒信使RNA）的原位杂交或免疫组织化学检测病毒核衣壳或刺突蛋白。如果上述方法是不可能的，逆转录聚合酶链反应检测或定量胎盘匀浆中的病毒RNA，或电子显微镜是替代方法。对胎盘感染的可能性进行分级分类，可能,可能，而且不太可能被提议。报告胎盘感染的手稿应描述取样方法（收集的样品的位置和数量），组织保存方法,和检测技术。对胎盘的处理提出了建议，考试,以及采样和使用经过验证的试剂和样品方案（作为附录包含）。
