Growth Trajectories of Children Born Preterm and Full-Term With Low Birth Weight to Preschool Ages: A Nationwide Study.

Context: Preterm (PT) and full-term with low birth weight (FT-LBW) children are at a high-risk of poor growth outcomes.

Objective: This work aimed to investigate the growth trajectories of PT and FT-LBW children from birth to preschool ages.

Methods: This study included 1 150 508 infants (PT, 41 454; FT-LBW, 38 250) who underwent the first 3 rounds (4-6, 9-12, and 18-24 months) of the National Health Screening Program for Infants and Children (NHSPIC). Growth measurements were obtained from the NHSPIC database and converted into Z-scores. Growth data at ages 2, 4, and 6 years were measured as outcome variables. The effect of being born small on poor growth outcomes was investigated using a generalized estimating equation and Cox proportional-hazards regression analysis.

Results: The median birth weights of the PT, FT-LBW, and FT groups were 2.3, 2.4, and 3.2 kg, respectively. The incidence of short stature (height Z-score < -2 SD score [SDS]) and failure to thrive (FTT) (body mass index (BMI) Z-score < -2 SDS) was the highest in the FT-LBW group, followed by the PT and FT groups. At age 4 years, the incidence rates were 6.0% vs 5.2% vs 1.9% for short stature and 4.6% vs 3.9% vs 1.7% for FTT. The β estimate of height outcome was lower both in the PT (-0.326 SDS) and FT-LBW (-0.456 SDS) groups.

Conclusion: The FT-LBW group was consistently shorter and lighter throughout the preschool period than the PT group, highlighting the significance of growth monitoring in high-risk populations.