Taking aspirin is associated with a 1 to 5% reduction in pre-eclampsia and a 1 to 5% reduction in premature births in women at high risk. The World Health Organization recommends low-dose aspirin for the prevention of pre-eclampsia in women at high risk and recommends it be started before 20 weeks of pregnancy. The United States Preventive Services Task Force recommends a low-dose regimen for women at high risk beginning in the 12th week. Benefits are less if started after 16 weeks. Since 2018 the American College of Obstetricians and Gynecologists has recommended low-dose aspirin therapy as standard preventive treatment for pre-eclampsia. There is a reported problem of its efficacy when combined with paracetamol. Supplementation of aspirin with L-Arginine has shown favourable results.
