My employer sacked me two weeks after informing them that I'm pregnant using a flimsy reason. Is this not a wrongful dismissal?

This is indeed a wrongful dismissal that triggers your entitlement to pay in lieu of notice and additional damages for breach of your right to be free from discrimination based on sex (pregnancy). Depending on your circumstances, you can pursue the case in civil court or through an application to the Human Rights tribunal/commission, so please give us a call to discuss the matter further and identify the course of action that best suits your situation.