With regard to your query regarding diagnosis of polycystic kidneys at 7 months of pregnancy, it is pertinent to know if any of the parents or grandparents too have this problem. The common form is usually inherited from either parents side, and problems come only after 3 or 4 decades of life. There may be cysts in other organs also. The uncommon form 1:10000, autosomal recessive can cause problems of renal disorder early, may be in neonatal period itself. Ultrasound cannot differentiate between the two types. You are advised to plan delivery at a centre with neonatal intensive care unit so that if there is any renal, breathing or other problem in the baby, the doctor can manage.