Small and colleagues (1987) reported that twice-weekly onstress testing in a corrected perinatal mortality rate of 4.3 per 1,000. and associates (1983) that natal mortality in postterm pregnancies was 2.1 per 1,000 using urinary estriol/creatinine ratios, 6.5 per 1,000 using the conaction stress test, and 24 per 1,000 using the nonstress test.