The peak height at 450 nm (? OD450) of amniotic fluid is obtained before the thirty-second week of pregnancy. This is divided into one of three decision groups based on the peak height.


Two or more determinations recommended for valid prognostication, since a single test result can be misleading.

? OD450


< 0.07

continued observation, with vaginal delivery at or near term

0.07 - 0.17

delivery should be accomplished between the end of the 34th week and beginning of the 38th week

> 0.17

immediate therapy, either intrauterine exchange if under 34 weeks or premature delivery if over 34 weeks


The first group had 100% survival, with some requiring intrauterine transfusion.


The second group showed about 75% survival with many infants requiring intrauterine transfusions. If sequential determinations of the ?OD450 are performed

(1) Those with the ? OD450 decreasing by at least 0.01 units per week had the lowest mortality (11%)

(2) Those with the ? OD450 increasing by at least 0.01 units per week had the highest mortality rate (64%)

(3) Those with the ?OD450 stable (not decreasing or increasing by more than 0.01 unit per week) had an intermediate mortality rate (31%)


The third group can be further subdivided into 3 groups (0.18 - 0.30, 0.31- 0.40, > 0.40) with increasing fetal mortality and need for intrauterine transfusion.



• The mortality rates observed today (almost 30 years later) would be decreased due to better intrauterine and neonatal management. However, the relative severity of the different groups are still pertinent.


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