Once again you're displaying your ignorance, although this time it's not entirely your fault.
I don't know how this whole debate started. I joined the USMC in 1982 and pregnant women served the whole time that I was in through '04. They have maternity uniforms that are just like their regular uniforms, just cut wider for the girth.
Your wording may be rough (yes, a uniform is always required, but they're available), but you're right, they are not useless.
Perhaps where the debate started was with sending pregnant women into combat. That's a whole 'nother can o' worms that I'm not touching. I think that it should be their choice, but if they choose to go into combat while pregnant then yes, they'll need a uniform.