Full term baby and then a very prem at 27weeks reason unknowm lots of bleeding prior also had a low laying placenta whats the chances of another prem?

Depends on why. It depends on why you had the premature baby. Fixable causes include intrauterine infection, cervical premature opening (incompetence) and trauma. Low lying placentas tend to migrate upwards in the uterus in the latter stages of pregnancy and if not the condition will announce itself with bleeding.