For reference, I'm 21weeks with my 5th, 5'5" and 155 lbs and ordered a medium. Usually ON sizes run a little larger than other brands on me, so I was expecting a slightly looser fit. The medium fits and has lots of stretch for the next 4 months, but is VERY fitted. (My "cheerio" of a belly button i...s very visible in the white lol) So if you're looking for a looser fit maybe size up. Otherwise these are great tops especially for the price! I will keep the ones I purchased but maybe order a couple larger in a month or so. This is likely my last baby so I just needed a few items to get me through the summer and these will definitely work for the hot Houston summer.