In marsupials, such as opossum and kangaroo, the life span of the corpus luteum is similar in pregnant and nonpregnant females.

在有袋目动物中，如负鼠和袋鼠，妊娠和非妊娠母兽的黄体存在时间相似。

So far, they've found that just as in rats, pregnant women perform worse on some learning and memory tasks than nonpregnant controls.

到目前位置，他们发现，就和大鼠一样，和没有怀孕的对照组相比，怀孕的女性在某些学习和记忆任务中的表象更糟。

But on behavioral measures, rat moms perform significantly better on spatial working memory tests than nonpregnant rats, with first-time moms performing the best of all.

但是在行为测量的维度，产仔的大鼠在空间工作记忆测试中的表现明显好过没有怀孕的老鼠，而第一次产仔的大鼠表现最好。