Table 3.

Predicted Probability of Neonatal Respiratory Distress Syndrome by Gestational Age and Lecithin/Sphingomyelin Ratio

Gestational age (wk)	Lecithin/Sphingomyelin Ratio
	1.0	1.2	1.2	1.6	1.8	2.0	2.2	2.4	2.6	2.8	3.0	3.2	3.4	3.6
<26	1.00	1.00	1.00	1.00	.999	.999	.999	.998	.997	.996	.993	.990	.985	.977
27	1.00	1.00	.999	.999	.999	.998	.997	.995	.992	.988	.983	.974	.961	.942
28	.999	.999	.998	.997	.996	.994	.991	.987	.980	.970	.956	.934	.904	.861
29	.998	.997	.996	.993	.990	.985	.977	.966	.950	.926	.892	.845	.783	.704
30	.995	.992	.989	.983	.974	.962	.943	.916	.878	.827	.759	.676	.579	.476
31	.987	.980	.971	.956	.935	.905	.863	.807	.734	.646	.547	.443	.345	.258
32	.967	.950	.927	.893	.847	.785	.700	.615	.513	.411	.316	.233	.168	.117
33	.917	.880	.829	.762	.679	.583	.480	.379	.288	.211	.150	.104	.071	.048
34	.809	.737	.650	.551	.447	.349	.261	.189	.134	.093	.063	.043	.029	.019
35	.619	.518	.415	.319	.236	.170	.119	.082	.056	.038	.025	.017	.011	.007
36	.383	.291	.213	.152	.106	.073	.049	.033	.022	.015	.010	.006	.004	.003
37	.192	.136	.094	.064	.043	.029	.019	.013	.009	.006	.004	.002	.002	.001
38	.083	.057	.038	.026	.017	.011	.008	.005	.003	.002	.001	.001	.001	<.001
39	.034	.022	.015	.010	.007	.004	.003	.002	.001	.001	.001	<.001	<.001	<.001
40	.013	.009	.006	.004	.003	.002	.001	.001	<.001	<.001	<.001	<.001	<.001	<.001

Values are expressed as probabilities. Bold values represent risk cutoff of less than 0.030 or 3%.