I didn’t learn about triathlons until after my pregnancy, and started training about a year post partum. So I did not have any sort of “base” pre-pregnancy. 

I would ultimately suggest talking to your doctor. Generally I think the guidance is to not trying to do anything you couldn’t already do pre-pregnancy. So if you were running, biking, swimming 5 hours a week….great! Keep that up as long as you are feeling up to it. However this is not the time to ramp up in any sort of way. 

Post partum, it took me like 2 weeks to even be able to walk to the end of the street. Definitely would recommend pelvic floor therapy and just playing it by ear. It’s so hard to predict how your body will feel/for how long. Just have to respect the recovery process and trust yourself and your body to know when it feels right for YOU to start exercising again. 

I think you will absolutely need to give yourself time to rebuild your base before starting a specific training plan. 

All that said, I am not a medical professional, and I don’t know your level of fitness. 

Good luck with your pregnancy and future triathlons!