What is the normal heart rate of a term fetus?

Abstract

c o R R E s P O N D E N c E Sir,The Editorial in the July issue of the Journal (Vol 103, July 1996) sets up a false dichotomy between pragmatic and explanatory trials. Pragmatic trials aim to see whether an intervention works in the real world rather than the ideal world. The entry criteria are therefore more relevant to the problems clinicians actually face. Explanatory and pragmatic trials have different questions to answer and therefore differ in terms of entry criteria, size and settings. Explanatory trials are useful in exploring the pathophysiology of disease and mechanisms by which an intervention can improve outcome and lead to pragmatic trials. The size of a trial, on the other hand, is relative and trials can only be appropriate or inappropriate size in relation to the question it is attempting to answer. Selection of appropriate research questions and outcome measures should lead to appropriately sized trials. Appropriate interpretation of trial results is also important. A well designed trial may give an equivocal result, either because the intervention has a very small effect, or because of an element of imperfection in the design and conduct of an intervention. At the same time we have to be clear that a negative finding is not an equivocal one. Rarely, if ever, are researchers in a position to predict the effect size with certainty. This is especially the case in pre-eclampsia, where there are many risk factors which may have different weights in different populations and, many unknowns about the pathophysiology of the disease still exist. Almost any biochemical, immunologic marker or measurement done in pre-eclamptic women is found to be abnormal. This is the case with prostacyclin-thromboxane imbalance. It is not easy to know for certain whether an abnormality is a significant contributor to the disease process, in which case interventions that are likely to correct the abnormality might be beneficial, or an epiphenomenon.In summary, we welcome the Editor's plea for more observational and explanatory studies, especially in women with pre-eclampsia. We hope, these will lead to good pragmatic trials designed through shared expertise from different specialties.

What is the “normal” fetal heart rate?

“…Therefore it seems natural to assume that further work on improving definitions and standardization by using computerized methods will further improve the monitoring systems. However, currently, there is not even agreement on the normal range of the baseline of the FHR, although, as Massaniev stated in 1996, “baseline rate provides valuable information on which we plan our further actions” (Manassiew, 1996). …”

Linear Phase Sharp Transition BPF to Detect Noninvasive Maternal and Fetal Heart Rate

“…Uncertainty regarding the diagnosis based on interpretation of FHR patterns has given rise to reassuring and nonreassuring patterns [ 6 ]. Reassuring FHR patterns include the normal baseline FHR, moderate accelerations, and variability with fetal movement assuring the well-being of the fetus, whereas nonreassuring FHR patterns include tachycardia (FHR baseline more than 160 bpm), bradycardia (FHR baseline is less than 110 bpm) [ 10 ], prolonged decelerations, and so on. The severe and prolonged hypoxia induces a prolonged fall in FHR [ 11 ].…”

Peer Review #1 of "What is the “normal” fetal heart rate? (v0.1)"

“…Therefore it seems natural to assume that further work on improving definitions and standardization by using computerized methods will further improve the monitoring systems. However, currently, there is not even agreement on the normal range of the baseline of the FHR, although, as Massaniev stated in 1996, ''baseline rate provides valuable information on which we plan our further actions'' [10].…”

“…This consensus replaced the former range of 120 to 160 bpm, as there was evidence pointing to worse fetal outcome for baselines higher than 160 bpm [20]. Up to now, ranges such as 110 to 150 bpm or 110 to 160 bpm [1,5,9,11,14,17,19,24] are also used, widely based on expert opinion rather than evidence.…”