针对当时居高不下的婴儿死亡率的翻译：At that time of high infant mortality rate 什么意思？中文翻译英文，英文翻译中文，怎么说？

青云英语翻译

Infant mortality was high for

At that time of high infant mortality rate

In view of infant mortality which at that time stayed at a high level

At that time against high infant mortality rate

At that time of high infant mortality rate