&NA;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‐PI (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.