Ageing placenta

I am 28 weeks and 4 days. Yesterday I went to the dr for my usual sono and check up, well the told me after my sonogram that I have an aged placenta and that it can cause baby to not get the oxygen and nutrients she needs. She said I have to see a specialist. She said that for now baby is doing okay and is in the 4th percentile. I was wondering if this has happened to anyone else and see if I can get some advice and your story's on what happened. Tia ❤