Modi twins worry. Please help.

Angie • Mother to a 👦👧👶👶 twinning is awesomeee
My twins have been doing good until today I got a scare. I'm 30 wks 1day and they are both growing normal. One weighs 3lbs 10oz and the other 3lb 6oz. Today the specialist came in and told me that everything was fine they are growing the way they are suppose to and everything else but he said he's concerned with baby B blood flow. But he said now to worry. I'm a little nervous. I had steroids shots on Friday. I'm a little nervous has this happen with anyone? Please give me advice. Thank you.