INTRODUCTION: While severe macroglossia in Beckwith-Wiedemann syndrome (BWS) is often treated with tongue reduction surgery, most patients with mild to moderate macroglossia are nonsurgically managed. Given that outcomes for these conservatively managed patients are not well characterized, this study aims to describe the natural history of patients with macroglossia and BWS who did not undergo early surgery. METHODS: Records of patients with BWS and macroglossia seen between 2004-2024 were reviewed. Conservative management was defined as not having had surgery during the first 3 years of life. Macroglossia was rated using the BWS Index of macroGlossia (BIG) scale to stratify phenotypic severity. Relationships among polysomnography data, surgical incidence, percentage mosaicism, and clinical scores were assessed. RESULTS: 320 patients with BWS and macroglossia were included, 231 (72.2%) of whom were conservatively managed. As BIG scores increased from BIG1 (mild) to BIG2 (moderate) to BIG3 (severe), both obstructive sleep apnea severity (P <
.001) and surgical incidence increased (P <
.001). Among conservatively managed patients, obstructive apnea-hypoxia index improved from 4.5 (interquartile range: 2.7-11.2) events per hour (age 0.4 [0.2-0.7] years) to 3.6 (1.3-6.1) events per hour (age 2.2 [1.7-2.6] years
P = .03). BIG scores also improved in this cohort from 2.0 (1.0-2.0) at 0.8 (0.4-1.5) years of age to 1.0 (1.0-2.0) at 2.6 (2.2-3.7) years of age (P = .02). CONCLUSION: Nonsurgical management in the first 3 years of life for mild and moderate macroglossia in BWS is associated with favorable outcomes. Obstructive sleep apnea and macroglossia often improve as the facial skeleton grows to accommodate the tongue.