My wife is now 7 month pregnant and every night she demand sex, I don't know how safe it is for her and the baby? Her tommy is big and she always want me on top. We got married 8 month ago. All I am affaid of is hurting the baby inside.

Baby is well protected... unless you were instructed by the doctor or midwife to refrain from having sex, it is fine. You just may have to adjust positioning for comfort... and feeling baby move in the midst of things can be a bit odd at times... :) Enjoy!