Sex during pregnancy after history of miscarriage

Hi ladies, i am currently 28 weeks pregnant with my rainbow baby after a miscarriage at 9 weeks a few months ago. My husband and i have abstained from sex as we are too nervous and dont want to affect this pregnancy. My placenta is prosterior 2.9cm from os and the only advice doctor told me was not to lift anything heavy. Have any of you gone through this and did you abstain until after birth?