Maternity leave discrimination in my project.

I am appalled by the decision of my project manager to allocate lesser band 'C' to women who are going for maternity leave in the next four months. This is a clear case of pregnancy and maternity discrimination, which is unlawful and unethical. These women have worked very hard and deserve fair treatment and recognition. I am so supprized by he's reason stating that they will eventually not going to part of our project at least this year so allocate them to next line persons so that we can encourage them (Here ntg wrong to encourage we can encourage multiple ways...) These bands belong to those womens who's still working with us more then 10hrs.

In this case what we can do...???