Fetal pulmonary maturity is characterized by which change in lipid indicators?

• A. Increases in PG and lecithin, while sphingomyelin remains constant
• B. Decreases in PG and lecithin, while sphingomyelin remains constant
• C. Increases in PG and lecithin, while sphingomyelin decreases
• D. Decreases in PG and lecithin, while sphingomyelin increases

Answer: (A)

Letal surfactant lipid changes reveal fetal lung maturity. As the lungs mature, production of surfactant ramps up, so lecithin (phosphatidylcholine) increases. Phosphatidylglycerol (PG) appears later and serves as a marker of mature surfactant systems. Sphingomyelin, a membrane lipid, does not change significantly with maturation. Therefore, the pattern of rising lecithin and PG while sphingomyelin stays constant best reflects pulmonary maturity, and this is the rationale behind selecting that option.