Can Long Term Use Of Heparin Cause Problem In Pregnancy?

Hi I am 23 wk 3 days pregnant.Due to i had a miscarriage this time doctor giving me heparin(Hef 25) 1 ml each day.It is already more than 4 month i am taking this injection daily.Is it safe to take this injection for such a long period.Doctor asked me to continue the same till 28th week and after that they will take any decission.Till now my Scan report,Blood report every thing is fine.Baby s growth is also good. Please tell me if any side effect for taking the injection for so long in future. Also I am taking Ecosprin 75 mg tablet daily at night.On the tablet it self it is mentioned not to take the tablet with in 3 month of delivery as it may cause bleeding in Mother and Baby.Please suggest if any problem in taking this.I am taking this from my 5 th week till now...23 wk 3 day Waiting for your reply Thanks Sangita