The best person to ask about supplements during pregnancy is your obstetrician, gynecologist, midwife, or whomever is supervising your pregnancy and delivery and their advice should supercede anything you read on the internet, here or otherwise. Baby aspirin at a dose of 81mg has been shown to be helpful for women with the MTHFR mutilation for preventing repeat pregnancy loss as well as decreasing the risk of preeclampsia. The American College of Obstetricians and Gynecologists suggests that for preeclampsia, 81mg baby aspirin should be taken daily until delivery.