If I'm pregnant and fell at the store but am okay, do I still have a case?

You almost certainly do not have a case:

1) The legal system only provides compensation for actual injuries or damages, including medical costs. If you are "ok," you might be able to recover for your out-of-pocket (i.e. not covered by insurance, like copayments) medical costs--but you'd have to sue to recover them. If your only "damages" are medical costs, then unless they ran to many hundreds or several thousands of dollars, it is difficult to imagine that legal action would be economically justified.

2) Moreover, the store would only be liable, or responsible to pay, if it was at fault in some way. The law does not make a person or business responsible for another's injuires simply because that person was hurt on another's property. Instead, there must be fault to be liability. So unless the store caused your fall in some way--such as by not cleaning up a spill which they knew or should have known posed a hazard--it would not be liable.