Hello everyone! Could someone tell me if they've experienced something…

Hello everyone! Could someone tell me if they've experienced something like this? The due date is 30 weeks. Ultrasound revealed pericardial effusion on the right side of the heart, measuring 4.5 mm. The doctor who did the ultrasound doesn't know what caused it and it might resolve itself. I am very worried about my baby. I read that if it doesn't resolve itself, they do a puncture. Girls, please share if you have had something similar.