I'm having one of those "taking over my head" days. Like you, mine started out of nowhere. I've been to the ER more times than I care to admit, and have had all the tests and blood work multiple times. The PACs/PVCs have shown up on both my 48 Holter monitor read out, and they've seen them on my 30-day event monitor, but like you, weren't concerned. I've had the EKGs, echo's, and even a stress test. All normal. Or normal enough for them not to worry. I've been told they may go away as quickly as they came, because they have no idea what started them.
Other than a stolen sip or two of my husband's soda, I haven't had a cup of caffeine since I had my gall bladder removed 5 1/2 years ago. I have had 1/4 glass of wine in the last 4 months (and generally only drank one night a month before then). It never happens when I'm working out.
Here's what I've been told: some people grow into out, and many grow out of it. We don't know what starts it, or why it stops, but it might. I'm holding onto that for dear life, along with the thought that I don't want this to CONTROL my life. I'd talk to your cardiologist about the pregnancy; hopefully it will all work out. Prayers to you!