Fetal cardiac interval recorder

A recorder is described which is capable of continuously measuring intervals between two events of the fetal cardiac cycle, as well as functioning as a routine intrapartum monitor. We have primarily measured the interval between the R wave of the fetal ECG and the second fetal heart sound (R-S2), but the recorder is also capable of measuring R-R, R-A0 (opening of aortic valve), R-Pl (placenta), and R-Sc (scalp) intervals. In the discussion, we endeavor to show that these intervals reflect fetal cardiac performance, which is altered by drugs and acidemia.