Final answer:
The L/S ratio, or lecithin to sphingomyelin ratio, is used to assess fetal lung maturity, with a ratio of ~2.5 indicating maturity, values between 2.4 to 1.6 indicating low risk, and less than 1.5 indicating a high risk for respiratory distress syndrome.
Step-by-step explanation:
The ratio used to measure fetal lung maturity is the lecithin to sphingomyelin ratio, commonly referred to as the L/S ratio. A mature fetal lung typically has an L/S ratio of approximately 2.5. A ratio that ranges from 2.4 to 1.6 indicates a low risk, whereas an L/S ratio of less than 1.5 suggests a high risk of infant respiratory distress syndrome (RDS). To mitigate the risks associated with immature fetal lungs, treatment options include administering steroids to the mother or infant to assist in lung development, application of surfactants, and utilizing a ventilator to support breathing when necessary.