Methods of fetal movement counting and the detection of fetal compromise

Abstract

Maternal perception of fetal movements is widely used as a marker of fetal viability and well-being. A reduction in fetal movements is associated with fetal hypoxia, increased incidence of stillbirth and fetal growth restriction (FGR). Therefore, a reduction in fetal movements has been proposed as a screening tool for FGR or fetal compromise. The problem of this approach is that there is no widely accepted definition of reduced fetal activity or 'alarm limits', and pregnant women are currently given a wide range of non-evidence-based advice. We have reviewed the background of published definitions and their potential usefulness in screening. A formal meta-analysis of these studies is not possible due to variation in methodology and definitions of reduced fetal movements. Assessment of fetal movements using formal fetal movement counting has shown equivocal results. Importantly, in all studies, there was a decrease in perinatal mortality suggesting a beneficial role for raising maternal awareness of fetal movements. Most studies implemented limits to define reduced fetal movements based on small groups of high risk pregnancies and obsolete counting methodology. A single case-control study developed 'normal limits' in a low risk population, and successfully implemented it prospectively for screening. At present, there is no evidence that any absolute definition of reduced fetal movements is of greater value than maternal subjective perception of reduced fetal movements in the detection of intrauterine fetal death or fetal compromise. Further investigation is required to determine an effective method of identifying patients with reduced fetal movements and to determine the best subsequent management.