Thanx for query.
As you told you are having cyst
on placenta,that is not a big problem,because your baby not having any sign of hydrops.It means their is no sign of throphoblastic disease.
The problem is your baby maturity,you should take proper diet,rest and steroid
for foetal lung maturity.your baby is not harm with cyst placenta,please take care of your diet,your baby will be fine.