[Short-term variability of fetal cardiac activity in 1F and 2F behavioral states].
The investigation revealed intraindividual differences in characteristics of the short-term variability of cardiac action of normal foetus during the tenth month of pregnancy in the phase of behavioural state 1F and 2F. These conditions, in particular state 1F, are otherwise frequently the cause of false positivity of the non-stress test during antepartum monitoring because the values of the parameter of short-term variability of FHR when reading the hard print of the cardiotocogram can permit also an interpretation suggesting the diagnosis of chronic foetal hypoxia. Simultaneously the authors proposed and tested a simple supplementing device which makes it possible to evaluate continuously selected parameters of the short-term variability of cardiac action for the needs of antepartum monitoring.