BACKGROUND: Epidemiological studies show that the height-for-age Z-scores (HAZ) falter dramatically shortly after birth until the end of the first two years. Understanding these changes in linear growth in the first two years can help us understand the critical period of child linear growth and propose interventions. OBJECTIVES: This study objectives were to describe the pattern of linear growth faltering and analyze the changes in length-for-age Z-scores (LAZs) throughout the first two years based on birthweight and length status. METHODS: This study analyzed 408 children, participants in Longitudinal Study on Child Growth and Development in Bogor, Indonesia. The linear growth pattern was described based on birthweight and length status. Birthweight and length status was categorized into normal and Small for Gestational Age (SGA). Changes in LAZs (Δ LAZs) in 0-6 months, 6-12 months, and 12-23 months were calculated. General Linear Model Univariate analysis was conducted to analyze the difference of Δ LAZ between SGA and normal children. RESULTS: Though full-term SGA children have significantly higher linear growth velocity during the first 6 months of the infancy period, full-term SGA children could not catch up with the attained growth/height of normal children throughout the first two years. Thus, full-term SGA children ended up with a higher prevalence of stunted. Both in SGA and normal children, the substantial loss of LAZ occurred between 0-6 months. CONCLUSION: The finding in this study showed that the first 1000 days of life is still the best period in stunting prevention; however, the stunting prevention program should start earlier, focusing on the first 500 days of life, and potentially the prenatal period.