The intrauterine environment was long considered sterile. However, several infectious threats are already present during fetal life. This review focuses on the postnatal immunological consequences of prenatal exposure to microorganisms and related inflammatory stimuli. Both the innate and adaptive immune systems of the fetus and neonate are immature, which makes them highly susceptible to infections. There is good evidence that prenatal infections are a primary cause of preterm births. Additionally, the association between antenatal inflammation and adverse neonatal outcomes has been well established. The lung, gastrointestinal tract, and skin are exposed to amniotic fluid during pregnancy and are probable targets of infection and subsequent inflammation during pregnancy. We found a large number of studies focusing on prenatal infection and the host response. Intrauterine infection and fetal immune responses are well studied, and we describe clinical data on cellular, cytokine, and humoral responses to different microbial challenges. The link to postnatal immunological effects including immune paralysis and/or excessive immune activation, however, turned out to be much more complicated. We found studies relating prenatal infectious or inflammatory hits to well-known neonatal diseases such as respiratory distress syndrome, bronchopulmonary dysplasia, and necrotizing enterocolitis. Despite these data, a direct link between prenatal hits and postnatal immunological outcome could not be undisputedly established. We did however identify several unresolved topics and propose questions for further research.

中文翻译：

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生理条件下和感染期间的人类围产期免疫力

宫内环境长期以来被认为是无菌的。然而，在胎儿时期就已经存在一些感染威胁。本综述重点关注产前接触微生物和相关炎症刺激的产后免疫学后果。胎儿和新生儿的先天性和适应性免疫系统均不成熟，这使得他们极易受到感染。有充分证据表明，产前感染是早产的主要原因。此外，产前炎症与新生儿不良结局之间的关联已得到充分证实。肺部、胃肠道和皮肤在怀孕期间接触羊水，很可能是怀孕期间感染和随后炎症的目标。我们发现大量研究关注产前感染和宿主反应。宫内感染和胎儿免疫反应得到了充分研究，我们描述了针对不同微生物挑战的细胞、细胞因子和体液反应的临床数据。然而，与出生后免疫效应（包括免疫麻痹和/或过度免疫激活）的联系却要复杂得多。我们发现了一些研究，将产前感染或炎症与呼吸窘迫综合征、支气管肺发育不良和坏死性小肠结肠炎等众所周知的新生儿疾病联系起来。尽管有这些数据，但仍无法毫无争议地建立产前感染与产后免疫结果之间的直接联系。然而，我们确实确定了几个未解决的主题，并提出了进一步研究的问题。