Here is an article that discusses Active.com's race insurance and the items it will not cover.
http://www.dcrainmaker.com/2012/12/thoughts-on-active-coms-new-race-insurance-policy.licy
Looking at that list, I am almost positive that they would not refund for the reasons that you state. It doesn't cover pregnancy or anything connected to pregnancy, and if not connected to that, it could be covered under a "pre existing condition". The race insurance seems to be geared toward an athlete developing a catastrophic injury, with no other reasons allowed.
And I know you didn't ask for advice on breastfeeding, but I'm just going to put this here.
http://kellymom.com/bf/can-i-breastfeed/lifestyle/mom-exercise/. Studies show that exercise does not affect supply as long as you adequately hydrate and are eating an extra 300-500 calories a day. Of course, I don't know all your details so take my unsolicited advice for what it's worth.