TOPLINE

Among more than 92,000 term-born children, smaller fetal size at birth was associated with lower academic performance in math and reading that persisted throughout adolescence, whereas those born at 37 weeks had poorer language and motor skills that largely faded by age 5 years.

METHODOLOGY

• Researchers conducted a longitudinal birth cohort study to examine the patterns and persistence of associations of gestational age and fetal size with neurodevelopmental outcomes from infancy through adolescence.
• They analyzed data from 92,551 term-born children (49.9% girls) without congenital malformations, drawn from a population-based health study in Norway.
• Mothers completed questionnaires around 15 weeks' gestation during pregnancy and at follow-up, providing information on demographic characteristics and their child's health and development, while fathers completed questionnaires on demographic characteristics.
• Gestational age was estimated from a routine ultrasound scan performed during 17-20 weeks of pregnancy and was measured across weeks 37-41; fetal size was measured as birth weight for gestational age and sex and categorized as small for gestational age (SGA), appropriate for gestational age (AGA), or large for gestational age (LGA).
• Primary outcomes included language and motor skills at 6 months, 18 months, 3 years, and 5 years, as well as national test scores in math and reading during late childhood and adolescence.

TAKEAWAY

• Children born at 37 weeks had poorer language skills from 6 months to 3 years (P ≤ .01 for all) and poorer motor skills from 6 months to 5 years (P ≤ .03 for all) than those born at 41 weeks; however, these associations diminished rapidly by 18 months of age and were attenuated by 5 years of age.
• Children born SGA had lower math scores from ages 10-15 years (P < .001 for all) and lower reading scores at ages 10-11 years (P < .001) and 14-15 years (P = .04) than those born AGA, suggesting that the association between smaller fetal size and academic performance persisted throughout adolescence.
• Those born LGA had slightly higher math scores at ages 14-15 years (P = .03) than those born AGA.
• Gestational age at term and fetal size were largely independent in their associations with neurodevelopmental outcomes.

IN PRACTICE

"These findings should inform obstetric counseling and shared decision-making rather than be interpreted as evidence supporting changes in delivery management," the authors wrote.

SOURCE

The study was led by Xuan Zhao, MSc, University of Warwick, Coventry, England. It was published online on August 26, 2026, in American Journal of Obstetrics and Gynecology.

LIMITATIONS

Follow-up rates declined over time, which may have introduced bias despite statistical adjustments for participant dropout. Fetal size was assessed using birth weight for gestational age because antenatal fetal size measurements were unavailable. Gestational age estimates relied largely on second-trimester ultrasound dating, which may have resulted in some exposure misclassification and underestimated the strength of the observed associations.

DISCLOSURES

Some authors reported support from the Chancellor's International Scholarship of the University of Warwick, the Big Baby 2 UP grant, and other sources. The authors reported having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.