Pregnant or Fat? Pregnant or Fat?

This afternoon a seat finally opens up at 14^th street on the packed 4 train. I leap into it, victorious! I look up and see a woman directly in front of me staring me down- she had wanted this seat too. Too bad. But as I observe her I notice she appears to be pregnant. Oh no- I am that asshole. Of course I would give up my seat to a pregnant woman. However the more I look up at her, the more unsure I am on whether she is actually pregnant or not. She is wearing one of those billowy loose tops that actually make most women look pregnant if they weigh over 105 pounds. I would definitely give her my seat- pregnancy confirmed or not but then I don’t want to insult her by implying I am giving her my seat because she is pregnant if she actually isn’t! Isn’t that the cardinal sin of…everything? Think a woman is expecting when she is just chubby? Do you see my dilemma?