I'm on aspirin to help prevent Pre eclampsia. My DD was born at 34 weeks due to severe pre-eclampsia and suffered from IUGR (she was 3lb 4oz so around 0.4th centile). Have been on aspirin since 12 weeks during this pregnancy. So far everything has been going really well, I have been having regular growth scans and this baby is growing perfectly (95th centile!) despite me having borderline high blood pressure throughout (my pre pregnancy BP is 110/60, during pregnancy 140-150/ 80-90) The purpose of the aspirin is to keep your blood thin so that even if there is a problem with the placenta the blood can travel to and from the baby more easily. In terms of side effects the only thing I have noticed is that my nose is bleeding almost constantly due to my blood being thinner but this is more annoying than anything else. Like any drug there are risks to taking it during pregnancy, as a previous poster said they wouldn't give it to you if the benefits didn't massively outweigh the risks, I think it is best to stay away from google! There is no way of knowing for sure but in my opinion it has helped me have a normal pregnancy and hopefully a large, healthy baby! x