Her muscle tone would be that good that she probably didn't notice any bulge. In any case, she's a fairly big girl for her size, given she's a weightlifter and the baby was small. He may not have been much larger even if she did carry him to term.
As a nurse I have seen this sort of thing many times. Atheletes especially can have totally irregular menstral cycles and may only have spotting when their menses is due. So as an indicator no flow is not accurate. Also as a 'Big Girl' she would not have shown a significant alteration in size. The baby was born at six months and was also not particularly big. I recently had a mother bring her 14 year old daughter to the emergency department with "stomache cramps" You guessed it she was about to deliver, much to the mother's surprise (and supposedly that of the daughter!).
I remember seeing a story once where this girl dropped to the ground and gave birth in a supermarket and kept insisting she wasnt when parademics where asking if she was pregnant and saying she was going into labour, denial is a powerful process!
