Postnatal development of rats born preterm and postterm. I. Body weight

Area of Science:

• Developmental Biology
• Neonatal Physiology
• Comparative Physiology

Background:

• Gestational age significantly influences neonatal development and growth trajectories.
• Understanding weight gain patterns in preterm, term, and postterm neonates is crucial for identifying potential developmental issues.

Purpose of the Study:

• To compare the postnatal growth patterns of preterm, term, and postterm rat pups.
• To investigate the impact of gestational variations on early-life weight gain and identify potential causes for growth discrepancies.

Main Methods:

• Litters were standardized with 3 preterm, 3 term, and 3 postterm littermates, each nursed by a single mother.
• Body weights were recorded from birth up to 30 postnatal days.
• Fetal and postnatal growth rates were analyzed across different gestational groups.

Main Results:

• Intrauterine weight gain in postterm fetuses was less than postnatal weight gain in term littermates.
• Preterm neonates exhibited a 3-day lag phase in postnatal weight gain compared to term and postterm groups.
• The initial growth deficit in preterm pups persisted for 30 postnatal days, suggesting early-life nutritional impact.
• A significant increase in weight gain was observed in all groups after day 20, coinciding with supplemental weaning diets.

Conclusions:

• Gestational age at birth critically affects early postnatal growth dynamics in rats.
• Early postnatal malnutrition significantly impedes weight gain in preterm neonates, with lasting effects.
• Supplemental nutrition during weaning can enhance growth rates in all groups, highlighting the importance of adequate nutrition during this period.