(317) Respiratory morbidity among offspring misclassified as growth restricted

An ultrasound-based diagnosis implies that some fetuses suspected to be growth restricted (IUGR) are discovered at birth to be appropriately grown (AGA birth weight, between 10th and 90th percentile). These fetuses may thus be exposed to unnecessary medical interventions such as antenatal corticosteroids administration and preterm labor induction. In this study we have evaluated the long-term respiratory health of misclassified IUGR offspring.

Study Design:

A population-based cohort analysis including deliveries of AGA singleton newborns between the 1991 to 2021 at a tertiary referral hospital was conducted. Incidence of hospitalizations due to various respiratory conditions was compared between AGA offspring with prenatal diagnosis of IUGR, and those without a diagnosis of IUGR. The Kaplan–Meier approach was used to estimate cumulative hospitalization incidence. The stratified Cox proportional-hazards model was used to control for confounders.

Results: A total of 324,620 deliveries of AGA newborns were included in the analyses, 3,249 of them (1%) were misclassified prenatally with IUGR. The IUGR subgroup delivered at an earlier gestational age (36.7 vs. 39.1 weeks, P< 0.001) and had more than 50% higher incidence of respiratory-related hospitalization during childhood (10.6% vs. 7.1%, P< 0.001; Table), as well as hospitalization related to asthma, bronchiectasis and obstructive sleep apnea (P < 0.05 for all; Table). Higher cumulative hospitalizations rate due to respiratory conditions was observed in Kaplan-Meier survival curve (log rank P -value < 0.001; Figure). This association between IUGR and respiratory morbidity was independent of gestational age and maternal age (adjusted HR = 1.17, 95% CI 1.05–1.30, P< 0.05), using a Cox proportional hazards model.

Conclusion: AGA newborns misclassified as IUGR, are at an increased risk for long-term respiratory morbidity during childhood and adolescence.