There are few safe, effective, and affordable interventions to improve pregnancy outcomes in low resource settings where the highest rates of poor birth outcomes occur. L-citrulline is naturally found in many foods and is changed into another important amino acid, L-arginine, in the body. L-arginine is important for the growth of a healthy placenta and healthy baby. Adding L-citrulline to the diets of pregnant women may be an effective and affordable way to improve the health of their babies.The goal of the AGREE trial is to test whether a dietary supplement containing a common food component, an amino acid called L-citrulline, can help pregnant Kenyan women at risk of malaria have healthier pregnancies and healthier babies. 2,960 pregnant Kenyan women will be enrolled and randomly assigned to take either a twice daily dietary supplement containing L-citrulline or a placebo supplement without additional L-citrulline. Maternal participants will be seen every month until delivery and at weeks 1 and 6 after birth. Infants will also be followed up at ages 6, 12, 18, and 24 months. The primary outcome of the study is 'adverse pregnancy outcome', a composite of foetal loss (miscarriage or still birth), preterm birth, low birth weight, small for gestational age or neonatal mortality. The results of the AGREE trial could help to guide obstetric and public health policy and provide a sustainable solution that could be implemented at the community level.