An analysis of the atropine test for placental transfer in 28 normal gravidas

The reaction of the fetal heart to maternally injected atropine from the fifth month of pregnancy on, is remarkably similar to that of the adult heart. When the reaction is clear-cut, there is an increase in rate and a decrease in the variability of the instantaneous rate. The reaction time is not influenced by the duration of pregnancy. Using several differently contrived end points to delineate the fetal reaction time, records from 26 of 28 normal gravidas could be read. Although the computer derived plots were readable in no greater percentage of cases than the analog tracings, they were far more definitive and easier to interpret. Analysis of the records of gravidas whose fetuses showed no readable response indicates that the trouble may lie in the concentration and speed of administration of the test dose of atropine.