What lab finding on amniocentesis indicates fetal lung maturity?

The laboratory finding that indicates fetal lung maturity is the surfactant/albumin ratio greater than 55. This ratio reflects the presence of pulmonary surfactant, which is produced by the fetal lungs and is crucial for the proper functioning of the alveoli after birth. Surfactant decreases surface tension in the alveoli, preventing their collapse and enabling the newborn to breathe effectively upon delivery.

As gestation progresses, especially after around 34 weeks, there is an increasing production of surfactant. Thus, measuring the surfactant/albumin ratio provides a reliable indicator of whether fetal lungs are sufficiently mature to function in air.

The other findings, while related to fetal lung maturity, do not provide as definitive an assessment as the surfactant/albumin ratio. For instance, a greater than 2:1 lecithin/sphingomyelin (L/S) ratio is also a common marker used to assess lung maturity but can have variability based on other factors such as the gestational age at which the amniocentesis is performed. Negative phosphatidylglycerol is associated with immature fetal lungs and means that lung maturity is not adequately attained. High albumin levels alone do not directly indicate lung maturity and can