Seperation anxiety

Ever since i got pregnant my 3 year old has been experiencing extreme seperation anxiety from me. I cannot drop her off at preschool without a full blown meltdown and her repeating that i can't leave her because she'll miss me. She's been in preschool for over a year now but this literally started since the day we told her we were pregnant. It's an exhausting 20 min process before i jusst leave her there screaming and run off to work which I'm always late for now. Any suggestions?