The significance of a low amniotic fluid creatinine and a mature lecithin/sphingomyelin ratio.

Creatinine levels were measured in 546 specimens of amniotic fluid with a lecithin/sphingomyelin ratio of 2.5 or more. With amniotic fluid creatinine levels below the normal range, 3 of 6 infants had major congenital abnormalities and two had severe rhesus isoimmunization; 3 of the infants died. Of 514 cases with amniotic fluid creatinine levels within the normal range (mean +/- 2 SD), 13 babies (2.5%) had major congenital abnormalities but only one of the babies died, giving a perinatal mortality rate of 0.2%. The significance of these findings is discussed.