Not a big sister yet...

So today my grandma came over and my daughter was wearing her "Big sister" shirt and my grandma says to her "why are you wearing that you're not a big sister yet". I'm due in 5 days and I thought it was kind of rude to say. The thing that throws me off the most is she's pro-life so shouldn't she realize life starts before birth? I take care of both of my kids and just because I can't hold 1 in my arms just yet doesn't mean I'm not a mother of 2. I feed him and take care of him and he wakes me in the night just as he will when he is out of me how is that not considered alive/here?