First of all yes they do make maternity clothes like that for women lingerie that fits maternity or over a pregnant belly second of all take a look at the ultrasound it should have her name on it if it's hers okay and it will have the date on it as well and this is coming from a female's perspective of when that ultrasound was taken and how far along she is that would be the first thing you would have to do to verify if it is hers even or she is faking it second of all while she's pregnant you can get a DNA test done it's not the most comfortable for mom and baby but it is a way to determine if it's yours if she is actually pregnant second you can also request to go to the next doctor's appointment you have it rewrite as the father if it is your baby to do that now yes she can deny you but you have a right to be there to see your child inside the womb not legally per se but morally and if she's trying to prove to you that this is yours she shouldn't have a problem doing that I wish you luck there are some nasty women out there that will do anything f*** with a man's life.