I think you need to be pretty careful about this. If you're saying making shoes is too physically intensive for any pregnant women, that's a pretty blanket statement. Some women are active until quite late into their pregnancy, and the idea that they might not be capable of making a shoe could seem quite insulting.

Also, presumably part of the appeal of this product is that your workers will receive better conditions than in horrible sweatshops. If you're saying that pregnant women are often exploited, but you won't let them work for you (and I may have misunderstood this) then aren't you dooming them to the conditions they already suffer, and denying them the chance to work for a better employer - you, in this case?