罗伯逊说，如果女方事先接触男方精液的时间达不到至少三个月，那么男方精子不能致孕的可能性更大。
"We used to think that if a couple couldn't get pregnant, and the man's semen test was normal, the problem lay with the woman. But it appears this is not always the case," Robertson said.
罗伯逊说：“我们过去认为如果一对夫妇不能怀孕，而丈夫的精夜化验结果又是正常的，那么问题就出在妻子身上。但看上去事实并非总是这样。”