The echo went well yesterday.
Segundo's premature beats meet all the criteria for benign arrhythmia. They're all atrial, which is good, and almost all conducted instead of blocked, which is also good (a few were blocked, but the cardiologist wasn't worried). Everything she could see looked normal. It's hard to perfectly measure fetal anatomy, because fetal circulation is different by nature, but everything looks normal right now.
There is still a small chance of the baby flipping into SVT. This is something that can also happen to kids and adults, and is usually very easy to treat, and sometimes people will flip in and out of it without any cause or intervention. Unfortunately, when fetuses flip into SVT, they can't get themselves out, so you have to treat the mama with Digoxin. Blech. The doctor said that, based on our echo and her experience, she thinks there's less than a 2% chance of that happening. The official statistic is 2-5%, but she feels our risk is lower than that. She just wants us to go for every two week heart rate checks (which only means one extra appointment, as I was due to start every two week appointments in December, oh my GOD where did the time go, I am SO not ready here!!!), and we go back for a repeat echo in 4-6 weeks. The arrhythmia could resolve by then, or it might persist until the baby is born and normal circulation takes over. Less than 1% of babies needs an echo or EKG after they're born- which, considering the number of babies who need those for other reasons, I'm not sure that's any higher than anyone else.
It's a lot of details to say, everything is FINE. We get an extra peek at the baby and one extra doctor visit, and one day, get to torture Segundo by telling him/her all the sturm und drang s/he caused before birth. Of course, I planned on telling Gracie the same thing about her choroid plexus cyst one day, and then she decided to make sure she gave us far better things to tell her about one day. So. Maybe I shouldn't plan on that...