Talk to Gynecologist on Clexan Side Effects During Pregnancy

doc recommend me clexane 40mg at 14weeks of pregnancy due to previous iud at 34 weeks there was Sever Iugr like gestational age was 34 weeks and as per ultrasound baby growth was only 25 weeks .Now in 2nd pergnancy as per doc for 2 weeks inject 40 mg of clexane on daily basis after that 4 injection in a week .slowly slowly dose will help me is there any side effect like kidney failure also another doc said that jusy take loprin and wait till 20 week if required then use clexane i am much confused and worried but i want to follow instructions of my doc plzzz guide me what should I do