Postmortem lung weight/body weight standards for term and preterm infants.

Area of Science:

• Perinatal pathology
• Neonatal development
• Pulmonary medicine

Background:

• Lung development assessment is critical in perinatal autopsies, particularly for preterm infants.
• Current diagnosis of lung hypoplasia in very premature infants (<28 weeks) relies on a lung weight/body weight (LW/BW) ratio of ≤1.5%.
• This threshold may be too strict for detecting milder forms of pulmonary hypoplasia, such as those associated with premature rupture of membranes.

Purpose of the Study:

• To establish normative reference values for postmortem lung weight to body weight (LW/BW) ratios in preterm and term infants.
• To assess the utility of these new reference values in identifying subtle pulmonary hypoplasia.

Main Methods:

• Retrospective analysis of fetal and newborn data (16-41 weeks gestation) without known risk factors for pulmonary hypoplasia.
• Calculation of mean LW/BW ratios across different gestational age groups.
• Correlation of LW/BW ratios in infants with risk factors (e.g., congenital diaphragmatic hernia, renal anomalies, prolonged rupture of membranes) with established reference values.

Main Results:

• Established normative LW/BW reference values for preterm and term infants across gestational ages.
• Identified significantly higher 10th percentile LW/BW values in preterm infants compared to term infants.
• Demonstrated that the traditional 1.5% LW/BW threshold missed subtle pulmonary hypoplasia in infants with prolonged rupture of membranes, whereas age-matched percentiles identified additional cases.

Conclusions:

• Determined new LW/BW reference values for postmortem lung assessment in infants.
• Age-matched LW/BW reference values are crucial for accurately evaluating lung growth, especially in preterm infants.
• Utilizing these reference values enhances the detection of subtle pulmonary hypoplasia, improving diagnostic accuracy in perinatal pathology.