(291) Late and Post-Term Birth and Endocrine Morbidity in Offspring: A Population-Based Study

Objective:
At term, the fetal endocrine system is well-developed and capable of supporting the transition to neonatal life, as most hormonal axes are active and functionally mature. However, post-term birth ( >42 weeks’ gestation) has been linked to various physiological stressors, and its association with long-term endocrine outcomes is unclear. We aimed to evaluate a possible association between gestational age at delivery and the risk of offspring long-term endocrine morbidity.

Study Design:

We conducted a retrospective, population-based study including all singleton births between 1991-2021 at a tertiary medical center. Offspring were stratified by gestational age into: full term (39.0–40.6 weeks), late term (41.0–41.6 weeks), and post-term (≥42.0 weeks). Long-term endocrine morbidity was identified through both inpatient and outpatient records. Cumulative incidence across gestational age groups was assessed using Kaplan-Meier survival curves. A multivariable Cox regression model was used to evaluate the independent association between gestational age and endocrine morbidity, adjusting for maternal and gestational age, gestational diabetes, hypertensive disorders, and mode of delivery.

Results:

A total of 103,797 singleton births beyond 39 weeks were included. The overall rate of endocrine morbidity was comparable between full-term, late-term and post-term offspring (Table). However, the cumulative incidence of endocrine morbidity over time was lower for offspring born late- and post-term (Figure), and the adjusted analysis found that late-term birth was associated with a decreased risk of endocrine morbidity (HR 0.79; 95%CI 0.69–0.89; p< 0.001), while post-term birth did not differ significantly from full-term (HR 0.77; 95%CI 0.57–1.05; p=0.101).

Conclusion:

Late-term birth appears to confer a modest protective effect against long-term endocrine morbidity in offspring, but this effect was not apparent for post-term births. Additional studies are needed to better elucidate whether prolongation of pregnancy offers any significant advantage to the offspring.