Introduction
Late preterm infants, defined as those born between 34 and 36 weeks of gestation, represent a significant proportion of preterm births worldwide. These infants often face unique challenges compared to full-term infants, including a higher risk of neonatal complications such as hypoglycemia. Neonatal hypoglycemia, characterized by low blood sugar levels shortly after birth, is a common metabolic issue that can potentially affect brain development and long-term neurodevelopmental outcomes.
Hypoglycemia during the neonatal period is concerning because glucose is the primary energy substrate for the developing brain. Prolonged or severe hypoglycemia might disrupt normal brain function and potentially lead to cognitive, motor, or behavioral impairments later in childhood. However, the relationship between transient neonatal hypoglycemia, especially in late preterm babies, and long-term neurodevelopment remains unclear.
Study Objective
The purpose of this prospective multicenter study was to evaluate whether neonatal hypoglycemia occurring in infants born to mothers at risk for late preterm delivery adversely affects childhood neurodevelopmental outcomes. Specifically, the study assessed children at six years or older to determine if hypoglycemia within the first 24 hours of life is linked to deficits in cognitive function or other developmental measures.
Methods
The research was part of a larger multicenter randomized clinical trial, the Antenatal Late Preterm Steroids trial, which studied steroid administration in late preterm deliveries. It involved 13 centers associated with the Maternal-Fetal Medicine Units Network, enrolled between 2011 and 2016. Follow-up evaluations for neurodevelopment were conducted from 2017 through 2022.
To participate in follow-up, informed consent was obtained from adults and assent from children when appropriate. The primary measure studied was neonatal hypoglycemia, defined as any recorded blood glucose level below 40 mg/dL within the first 24 hours after birth.
The primary outcome analyzed was the proportion of children with a General Conceptual Ability (GCA) score below 85 (more than one standard deviation under the mean) measured using the Differential Ability Scales, Second Edition (DAS-II). This cognitive assessment provides a broad evaluation of intellectual functioning.
Secondary outcomes included assessments of motor function using the Gross Motor Function Classification System (GMFCS), social responsiveness using the Social Responsiveness Scale, Second Edition (SRS-2), and behavioral assessments via the Child Behavior Checklist (CBCL).
Statistical analysis included both univariable and multivariable models. Multivariable analyses adjusted for predetermined factors known to influence neurodevelopment, such as maternal age, socioeconomic status, treatment group, and ethnicity.
Results
The study enrolled 1,026 children, with nearly complete blood glucose data available for 1,020 (99.4%) and primary outcome data available for 944 children. Among those assessed, 83.2% were delivered late preterm, and 22% experienced neonatal hypoglycemia. Of the hypoglycemic infants, approximately 40% received treatment for low blood sugar.
Demographically, infants with hypoglycemia tended to have older mothers, were more likely to be White, had private insurance, and more frequently were born to mothers who received antenatal betamethasone treatment.
Crucially, no significant differences were found in primary cognitive outcomes between children who experienced hypoglycemia and those who did not. Specifically, 15.9% of hypoglycemic children had GCA scores below 85 compared to 18.5% of non-hypoglycemic children. The adjusted relative risk was 1.03 with a 95% confidence interval of 0.74 to 1.45, indicating no statistically significant increased risk associated with hypoglycemia.
Secondary outcomes evaluating motor function, social responsiveness, and behavioral patterns similarly showed no differences related to neonatal hypoglycemia. Additionally, severity of hypoglycemia, including lower glucose thresholds or extended duration, did not correlate with adverse outcomes.
Discussion
This study provides reassuring evidence that transient hypoglycemia in late preterm infants does not appear to negatively impact cognitive, motor, or behavioral development by early school age. These findings are important for clinicians and parents managing late preterm infants, as they suggest that mild to moderate hypoglycemia treated appropriately may not entail long-term neurodevelopmental harm.
It should be noted that this study benefits from a large sample size, standardized neurodevelopmental assessments, and adjustment for multiple confounders, strengthening the validity of its conclusions. The use of a well-characterized cohort enrolled in a randomized trial setting adds to the robustness of the findings.
However, there are limitations to consider. The study cohort was predominantly late preterm infants, so these results may not be generalizable to markedly preterm infants or those with severe neonatal illness. Furthermore, the hypoglycemia episodes were managed according to standard clinical protocols, so outcomes may differ in settings with less access to early detection and treatment.
Clinical Implications
For healthcare providers, these results support current practices of screening and managing neonatal hypoglycemia in late preterm births without undue concern for detrimental neurodevelopmental sequelae if promptly treated. Continual monitoring and follow-up remain essential to ensure children develop appropriately, but mild neonatal hypoglycemia alone should not raise alarm for neurodevelopmental deficits.
Parents can be reassured that brief episodes of low blood sugar in their late preterm newborns, when addressed effectively, are unlikely to impact their child’s intelligence, motor skills, or social behaviors in early childhood.
Conclusion
In this multicenter prospective cohort study, neonatal hypoglycemia in predominantly late preterm infants was not associated with adverse neurodevelopmental outcomes by six years of age. These findings alleviate concerns about long-term developmental harm from hypoglycemia in this population when managed according to current standards.
References
Gyamfi-Bannerman C, de Voest JA, Tita ATN, et al. Child Neurodevelopmental Outcomes After Late Preterm Hypoglycemia. Obstetrics and Gynecology. 2026 Jul 16. PMID: 42462244.
