Comparison of early growth and development in very preterm children in the Netherlands between the 1980s and 2000s

Since 1990, the survival rate of very preterm (VP) infants (born < 32 weeks of gestation) has significantly improved due to advancements in neonatal care practices. This study aimed to investigate whether these medical advances have translated into better growth and neurodevelopmental outcomes during the early life of VP children.

A comparative analysis was performed using data from two community-based studies: POPS (1983) and LOLLIPOP (2002/2003). A total of 1,294 very preterm (VP) infants provided data on height, weight, and head circumference during the first two years of life, as well as fine motor skills, gross motor skills, and communication milestones at 24 months of age. Rigorous harmonization procedures were applied to ensure comparability, including the standardization of growth metrics and consistent definitions for neurodevelopmental milestones across cohorts. Analyses were adjusted for higher parental education, severe intraventricular haemorrhage (IVH) and extended neonatal hospital stay to uncover if improvements reduce the differences in growth and neurodevelopment.

The LOLLIPOP cohort showed better height and weight growth trajectories within the first 24 months of life, even after controlling for sociodemographic and neonatal factors. Differences in head circumference trajectories were significant in unadjusted analyses but lost significance when adjusted for higher parental education, severe IVH, and extended hospital stays. Neurodevelopmental milestones, particularly gross and fine motor skills (e.g., "imitates others" and "squats or bends to pick things up"), improved in the LOLLIPOP cohort but were attenuated after adjustment. Substantial delays in communication (e.g., "says sentences of two words") and gross motor milestones (e.g., "walks well alone") were observed across both cohorts compared to the norms derived from full-term children.

VP infants born in the 2000s exhibited modest improvements in growth outcomes compared to those born in the 1980s. Reductions in neurodevelopmental impairments for the VP infants born in the 2000s are associated with higher parental education levels and reduced neonatal complications. Despite these advancements, persistent delays in cognitive and motor development underscore the necessity for early and targeted interventions to support VP children effectively.