他们认为，放松筛选严格性是一种母体的选择性反应，这可以解释唐氏综合症发病率随母亲年龄增长而升高的原因。

They believe that this relaxed filtering stringency is an adaptive maternal response and it might explain why the rate of Down Syndrome accelerates with increasing maternal age.

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孕期中的感染，增加母体与生产前后发病率与死亡率的风险。

Infections during pregnancy confers increased risk of maternal and perinatal morbidity and mortality.

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