The riskiest moment in any human pregnancy is arguably when the fertilized egg attaches to the womb wall and tries to establish a lifeline between embryo and mother. About half of in vitro pregnancies fail during this implantation stage, and many natural pregnancies end then as well. Now, researchers comparing pregnancy in opossums and several other mammals have shown how precise control of an immune process, inflammation, is critical to success or failure. In work reported at the annual meeting of the Society for Integrative and Comparative Biology in San Francisco, California, a Yale University team found that so-called placental mammals have tweaked an ancient inflammatory process to enable embryos to implant and persist in the womb. Placental mammals—named for the mass of tissue in the uterus that serves as the interface between mother and fetus—have specialized uterine cells that suppress the release of a key immune-stimulating molecule. This suppression may help delay the rejection of the embryo until it9s fully developed, they reported.

中文翻译：

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驯服的免疫反应有助于怀孕

人类怀孕中最危险的时刻可以说是受精卵附着在子宫壁上并试图在胚胎和母亲之间建立生命线。大约一半的体外妊娠在这个植入阶段失败，许多自然妊娠也随之结束。现在，研究人员比较负鼠和其他几种哺乳动物的怀孕已经表明，对免疫过程、炎症的精确控制对成功或失败至关重要。在加利福尼亚州旧金山举行的综合与比较生物学学会年会上报告的工作中，耶鲁大学的一个团队发现，所谓的胎盘哺乳动物已经调整了一种古老的炎症过程，使胚胎能够植入并留在子宫中。胎盘哺乳动物——以子宫内作为母体和胎儿之间界面的大量组织命名——具有专门的子宫细胞，可以抑制一种关键的免疫刺激分子的释放。他们报告说，这种抑制可能有助于延迟胚胎的排斥反应，直到它完全发育。