To determine which lecithin/sphingomyelin (L/S) ratio is indicative of fetal lung maturity, we need to understand the significance of different L/S ratios.
1. 1:1 - This ratio indicates an equal amount of lecithin and sphingomyelin. It is typically seen earlier in fetal development and is not indicative of fetal lung maturity.
2. 1.4:1 - This ratio shows a slightly higher amount of lecithin compared to sphingomyelin but is still not high enough to indicate fetal lung maturity.
3. 1.8:1 - This ratio is nearing the threshold but still falls short of the level considered indicative of fetal lung maturity.
4. 2:1 - This ratio means that the amount of lecithin is double that of sphingomyelin. Medical research and studies have shown that an L/S ratio of 2:1 is considered indicative of fetal lung maturity. At this ratio, there's sufficient lecithin present to ensure that the fetal lungs are mature enough to function effectively outside the womb.
Therefore, the lecithin/sphingomyelin (L/S) ratio indicative of fetal lung maturity is 2:1.