(17α)-13-Ethyl-10,17-dihydroxy-18,19-dinorpregn-4-en-20-yn-3-one;10β-Hydroxy D-(-)-Norgestrel;10β-HydroxyLevonorgestrel;13-Ethyl-10,17-dihydroxy-18,19-dinor-17α-pregn-4-en-20-yn-3-one;10-beta-Hydroxy Levonorgestrel;Levonorgestrel Impurity I (EP);Levonorgestrel EP impurity I;Levonorgestrel EP Impurity I (10-beta-Hydroxy Levonorgestrel)