Fraud is intentionally misrepresenting information in order to affect how the other party would act to cause a financial gain/loss. It is illegal for the other party to change how they act based on information about a pregnancy, therefore there is no legally admissible injury to the company. Legally, you're probably in about the same situation as a drug dealer accusing someone of stealing some of his goods - if you can prove that they actually caused you damages (ie: that you had a stash of drugs, or that you would deliberately not hire a candidate because they were pregnant), you're worse off than before.