My WTE app said that working out regularly during pregnancy will help your baby STTN sooner, be less prone to colic and better able to soothe themselves.

I worked out/ran 4-5 days a week up to my 9th month when I was pregnant with W and I can say that all of those statements were false for us. I haven't been able to do much this pregnancy (maybe 1-2x/wk), so we'll see how the next one is.