Pregnancy Discrimination?

In the United States it is technically illegal for an employer to discriminate against a pregnant woman. However, I can tell you that the HR manager from my old job would do anything in her power to find someone "better qualified" than the pregnant candidate. I think it is wrong to do this, but I can also see the side of the employer to an extent. If you hire a pregnant woman, you automatically have less than 9 months before she will go on maternity leave, and then she may or may not come back. It can be hard to keep training new people and so I can somewhat understand wanting to not hire pregnant if possible. But I still think it's overall wrong.