Developmental Milestones for Children With Down Syndrome: Revised Estimates Using Moving Average Summaries

Area of Science:

• Developmental Pediatrics
• Genetics
• Biostatistics

Background:

• Children with Down syndrome exhibit unique developmental paths.
• Specialized monitoring and counseling are crucial for these children.
• Previous estimates relied on generalized linear mixed-effects models (GLMM).

Purpose of the Study:

• To provide updated estimates of developmental milestone attainment in Down syndrome.
• To compare nonparametric approach estimates with prior GLMM estimates.
• To identify factors influencing developmental trajectories.

Main Methods:

• Reanalyzed data from 842 children with Down syndrome (2 months to 24 years).
• Calculated milestone achievement rates in 0.5-year windows.
• Employed shape-constrained additive models for monotonic regression curves.

Main Results:

• Nonparametric approach predicted earlier milestone attainment for 17/25 milestones compared to GLMM.
• Gross motor milestones showed consistent patterns; complex skills varied by model.
• Females achieved 17/25 milestones at least one year earlier than males.

Conclusions:

• Significant developmental heterogeneity exists in Down syndrome.
• Skill acquisition continues throughout childhood and adolescence.
• Updated estimates offer valuable clinical reference points for care and counseling.