Cystic mass

I’m a FTM and 31W4D, I have to go to a specialist because I’m 35 and that’s considered high risk. I had an ultrasound today and they found a cystic mass in the baby’s abdomen. The doctor went over it and said he’s 95% sure it’s an ovarian cyst and they are common with female babies because the hormones combining. He said that it looked benign, no irregularities or anything and that I shouldn’t worry. That it should go away within a month or two of her being born. And I have an ultrasound in four weeks to monitor it and see if it’s changed in size. It has not shown up in any other ultrasound and he said that was positive news. And after she is born they will do an ultrasound on her to see exactly where it is at if it has dissolved on its own. Anyone else ever gone through this?