2014 Clinical Guideline on Low-Dose Aspirin for Prevention of Preeclampsia1 Guiying Li, Department of Obstetrics and Gynecology, Obstetrics and Gynecology Hospital, Fudan University Recently, the United States Preventive Services Task Force (USPSTF) released the 2014 Clinical Guideline on Low-Dose Aspirin for Prevention of Preeclampsia, which is an update of the 1996 recommendations for aspirin prophylaxis during pregnancy. This update fully evaluates and considers the effectiveness of low-dose aspirin in women at increased risk for preeclampsia and the risks to the mother and fetus, and recommends a population of asymptomatic pregnant women at increased risk for preeclampsia with no prior adverse reactions or contraindications to low-dose aspirin. This article outlines a short list of indications for asymptomatic pregnant women at high risk for preeclampsia Recommended Low-dose aspirin (81 mg/d) after 12 weeks of gestation, Level of Evidence B Risk assessment 1. at high risk for one or more of the following risk factors: 2. 1. previous history of preeclampsia, especially if accompanied by an adverse outcome 3. 2. multiple pregnancies 4. 3. chronic hypertension 5. 4. type 1 or type 2 diabetes mellitus 6. 5. Autoimmune disease (e.g., systemic lupus erythematosus or antiphospholipid antibody syndrome) Preventive medication Low-dose aspirin (60-150 mg/d) starting at 12-28 weeks of gestation in women with high-risk preeclampsia to reduce the incidence of preeclampsia, preterm delivery, and intrauterine growth retardation (IUGR) Trade-offs Daily low-dose aspirin in women with high-risk preeclampsia There is a clear net benefit in reducing the risk of preeclampsia, preterm birth, and intrauterine growth retardation in women with preeclampsia Other Recommendations The USPSTF recommends an additional 0.4-0.8 mg of folic acid daily supplementation for all women who are planning or capable of becoming pregnant I. Basic Description 1. Pre-eclampsia as a complication has an impact on maternal and infant disability and mortality, affecting 2%-8% of pregnant women worldwide, and 15% of preterm births in the United States are due to pre-eclampsia. Pre-eclampsia is defined as the development of hypertension (blood pressure >140/90 mm Hg) and proteinuria (24h urine protein ≥0.3g) after 20 weeks of gestation. In the absence of proteinuria, preeclampsia is classified according to the presence of hypertension accompanied by any of the following conditions: thrombocytopenia; impaired liver function; renal insufficiency; pulmonary edema; and cerebral or visual dysfunction. 2. Risk status Important risk factors for preeclampsia include: previous history of preeclampsia (including early onset preeclampsia), intrauterine growth retardation (IUGR), preterm delivery, placental abruption or stillbirth, maternal co-morbidities (chronic hypertension, type 1 or type 2 diabetes, renal disease, autoimmune disease), and multiple pregnancies. Risk prediction models combining risk factors such as serum markers, uterine artery Doppler ultrasound, clinical history, and testing indicators are under development; no model with accurate prediction is currently available for clinical use. 3. Benefits of Prophylaxis The USPSTF found sufficient evidence that women at high risk for preeclampsia showed significant benefit from low-dose aspirin therapy to reduce the risk of preeclampsia, preterm delivery, and intrauterine growth retardation. In clinical trials, low-dose aspirin (60-150 mg/d) reduced the risk of preeclampsia by 24%, the risk of preterm birth by 14%, and the risk of intrauterine growth retardation by 20%. 4. The USPSTF found sufficient evidence that low-dose aspirin as a prophylactic agent does not increase the risk of placental abruption, postpartum hemorrhage, and fetal intracranial hemorrhage. In a Meta-analysis of randomized controlled studies and observational studies, aspirin was found not to significantly increase the risk of these adverse events in women with low-risk/intermediate/high-risk preeclampsia. In addition, there was no significant difference in the risk of placental abruption at different doses of aspirin. There is sufficient evidence that low-dose aspirin used as a prophylactic agent in women at increased risk for preeclampsia does not increase perinatal fetal mortality, and the USPSTF considers the harm of low-dose aspirin during pregnancy to be negligible. The USPSTF used “moderate certainty” to conclude that there is a clear net benefit of daily low-dose aspirin in reducing the risk of preeclampsia, preterm delivery, and intrauterine growth retardation in women at high risk for preeclampsia.