know someone who wants to keep swimming during her pregnancy is and looking for a nice maternity swimsuit - any recommendations?

Costco Speedos...typically the older women get these, but they fit great...will stretch as you stretch! Awesome price...typically around $20

It's not the fact that the "exercise" of participating in a tri would be the issue if you are someone who normally trains and exercises as intensely as you would need to in preparation.  A good rule of thumb is not to start something NEW when pregnant.... your body's in a hyperdynamic state from the pregnancy as a baseline.

I think the concern would lean more toward risk of physical injury.  You would have less of a risk for injury if the sprint swim portion is in a pool, and running may not be a problem, provided the course isn't a steep trail, but certainly, the risk from biking would be something to take into consideration.  And, if it's a sprint, you KNOW that there will be plenty of "newbies" in the crowd that may not have much biking experience to not be considered a risk (it may not really matter what YOUR biking experience is... when there are a lot of new folks around, there can still be accidents).  There are so many injury possibilities that can result from a fall from a bike....... and unfortunately, you can't go back and change the outcome, once the damage is done.  I would think it's better to play it safe and keep the training up (train on a bike trainer indoors until it becomes real uncomfortable, then just stop for the end of the pregnancy), but seriously take all of these factors into consideration before making your final decision. 

Best of luck with your pregnancy!