STUDY AIMS AND OBJECTIVES: 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.

METHODS: 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. The intervention consists of sachets containing a powder formulation of either L-citrulline or a matching placebo that is nearly tasteless and can easily be mixed with food or added to drinks. Maternal participants will be seen every month until delivery and at weeks 1 and 6 after birth. The newborns will be seen at birth, around 1 and 6 weeks after birth, and then at ages 6, 12, 18, and 24 months. The main outcome of the study is ‘adverse pregnancy outcome’, which includes loss of the baby (miscarriage or stillbirth), or if the baby is born too early or too small. The study will monitor factors in the mother’s blood that indicate how well the placenta and mother’s blood vessels are working, how much inflammation is in her body, and how her body is using L-citrulline and its impact on her breastmilk. The researchers will also examine the effect of the supplements on the baby’s survival after birth, the bacterial flora of the mother’s vagina and in her and her baby’s gut (microbiome), the impact of COVID-19 on the effect of nutritional supplements, and the child’s neurologic development in the first two years of life.

POTENTIAL APPLICATIONS AND BENEFITS: 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 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.

L-arginine is an essential amino acid in pregnancy and a key mediator of placental development and function. In many low-resource settings, widespread protein undernutrition contributes to L-arginine deficiency in pregnancy which is associated with an increased risk of adverse pregnancy outcomes. Using a preclinical model, we have previously shown that dietary L-arginine supplementation enhances placental vascular development and improves pregnancy outcomes. L-citrulline is an amino acid that is efficiently converted to L-arginine in the body and has a more palatable flavour profile.

PRIMARY OBJECTIVE: To determine if daily antenatal oral supplementation with L-citrulline can reduce adverse pregnancy outcomes (defined as a composite of fetal loss, infants born preterm, small for gestational age or with low birthweight) among pregnant women at high risk of malaria and protein undernutrition in Kenya.

OVERVIEW OF STUDY DESIGN: This is an individually randomized, two-arm, parallel-group, placebo-controlled clinical trial involving 2,960 pregnant women randomly assigned (1:1) to one of two study arms: i) L-citrulline arm –twice daily 6.0 g sachet, each containing 5.00 g of quality-assured L-citrulline powder, 0.66 g maltodextrin and 0.30 g lactose anhydrous, 0.03 g citric acid, 0.01 g lemon flavour + antenatal standard of care with enhanced monitoring (n=1,480); or ii) Placebo arm: 6.0 g sachet of quality-assured placebo, each consisting of 3.6 g maltodextrin and 2.4 g lactose monohydrate, 0.03 g citric acid, 0.01 g lemon flavour + antenatal standard of care with enhanced monitoring (n=1,480). All participants will continue to take the assigned product for 6 weeks after delivery and will receive an enhanced antenatal standard of care. The primary outcome is the clinical composite ‘adverse pregnancy outcome’. Secondary outcomes include longitudinal assessments of physiological and molecular markers of endothelial function, angiogenesis, inflammation, placental function, L-arginine metabolism, neonatal sepsis, mortality, and early childhood neurocognitive development to age 24 months. The effect of L-citrulline supplementation on the composition of the participants’ vaginal microbiota and the intestinal microbiota of both the participants and their newborns will be analysed in a subset of 132 mother/infant dyads. All maternal participants of the AGREE trial will be followed for 6 weeks post-partum and the children will be followed until age 2 years. Written informed consent will be obtained.