Which treatment has been shown to reduce risk for preterm birth, small for gestational age infants, and fetal or neonatal deaths?

• A. Low-dose aspirin
• B. Folic acid
• C. Supplemental calcium
• D. Antioxidant vitamins C and E

Answer: (A)

Low-dose aspirin works to improve placental blood flow by reducing platelet aggregation and shifting the balance away from vasoconstriction in the placental vessels. In pregnancies at risk for placental dysfunction, this improved placental perfusion lowers the risk of preeclampsia, which is a major driver of preterm birth, fetal growth restriction (small for gestational age), and fetal or neonatal death. Large studies and guidelines support starting low-dose aspirin in the first trimester for high-risk women to reduce these outcomes. By contrast, folic acid mainly prevents neural tube defects, calcium helps only in specific populations to reduce preeclampsia risk, and antioxidant vitamins C and E have not shown a benefit for these obstetric outcomes. Thus, low-dose aspirin best fits the question’s reported reductions.