Final answer:
Fetal lung maturity is assessed by measuring lamellar body count in amniotic fluid, which reflects surfactant levels in the lungs. A high count suggests mature lungs while low counts can indicate the risk for respiratory distress syndrome, potentially requiring treatment with steroids, surfactant, or ventilation.
Step-by-step explanation:
Fetal lung maturity (FLM) can be assessed using lamellar body count which evaluates the presence of surfactant-rich lamellar bodies in the amniotic fluid. Surfactant is a lipid substance that aids in lowering surface tension in the lungs and is crucial for proper lung function after birth. Lamellar bodies are similar in size to platelets and can be quantified using automated platelet counters. An increase in lamellar body count is indicative of greater amounts of surfactant, suggesting enhanced fetal lung maturity.
The lecithin to sphingomyelin ratio (L/S ratio) is a conventional test for assessing FLM. In mature fetal lungs, this ratio is approximately 2.5. Having a ratio between 2.4 and 1.6 indicates a low risk, while a ratio below 1.5 signifies a high risk of infant respiratory distress syndrome (RDS). If FLM is insufficient, treatment options include administering steroids to the mother or the infant to promote lung development, application of surfactants directly into the infant's airways, and supportive care using a ventilator.
From around the 24th week of pregnancy until term, the respiratory system undergoes significant growth and maturity. Adequate levels of surfactant for effective lung compliance are usually not achieved until about the eighth month of gestation. The production of surfactant continues, and alveolar precursors develop, becoming mature enough to permit a premature baby born around week 28 to typically breathe independently. However, the full complement of functional alveoli doesn't appear until around 8 years of age, highlighting the importance of the prenatal and postnatal periods for lung development.