The prevalence of stunting in young Indonesian children is the highest among Southeast Asian Nations, and is associated with poor growth during the prenatal and early postnatal periods. A maternal mentoring program was developed for Indonesian women to improve birth outcomes. A cluster randomized control trial (CRCT) was conducted in three sub-districts of the Special Re-gion of Yogyakarta, Indonesia. A total of 384 eligible participants were randomly allocated to either intervention (received maternal mentoring program and standard care; n=189) or control (received standard care only; n=195). The maternal mentoring program provided preconception health education; health monitoring; and text message reminders for preconception women. Fetal growth was measured between gestational weeks 27-30 using estimated fetal weight generated from ultrasonographic measurement. Birth weight was measured within 24 hours of birth. A structured questionnaire captured women’s’ demographics, pregnancy readiness, and body mass index (BMI. After adjustment, fetal weight was 14% (95% CI: 5.1-23.0) higher in the intervention group than in the control group, and the average weight-for-length Z-score at birth was 0.16 (95% CI: 004-0.30) higher in the intervention group than in the control group. A maternal mentoring program was associated with improved fetal growth and birth weight in this population.