Longitudinal Study of Fetal Body Movements: Nomograms, Intrafetal Consistency, and Relationship with Episodes of Heart Rate Patterns A and B

Abstract

Our objective was to investigate the longitudinal development of incidence parameters of fetal body movements to define normal reference ranges, to relate them to episodes of fetal heart rate patterns A and B, and to determine the intrafetal consistency for these parameters. Twenty-nine fetuses were studied longitudinally from 24 wk of gestation. Fetal body movements and heart rate were recorded at fortnightly intervals between 24 and 36 wk of gestation and weekly from 36 wk of gestation. Data were analyzed using multilevel analysis. Reference ranges were constructed for the percentage of observation time that movements were present, the number of movement bursts per hour, the mean burst duration, and the median onset-onset interval. The median percentage incidence of fetal body movements decreased from 17% at 24 wk to about 7% near term. The developmental course was the same during active episodes. Body movements also decreased during episodes of relative quiescence, in the course of pregnancy. Intrafetal variance was on average 40 -80% of the total range of the four movement parameters. Normal reference ranges were developed for incidence parameters of fetal body movements from 24 wk of gestation onward. The overall decline in the incidence of movements during pregnancy appeared to be a developmental phenomenon and not due to progressively increasing episodes of fetal quiescence. Individual fetuses showed a degree of consistency in the percentage incidence of body movements, but intra-and interfetal variances were generally high, resulting in wide ranges. (Pediatr Res 52: 568-575, 2002) Abbreviations FHR, fetal heart rate FHRP, fetal heart rate patternThe majority of neurodevelopmental disabilities have been estimated to originate from prenatal factors (1). Both the quantity and quality of fetal body movements have been recognized as important indicators of fetal well being and of the integrity of the CNS (2, 3). Studying fetal body movements could therefore provide a key to elucidate the prenatal etiology and pathogenesis of abnormal neuromotor development, which might, eventually, facilitate early intervention and optimal treatment before, during, and after birth. There is evidence that the quality of fetal body movements is more likely an indicator of brain integrity than the quantity of movements (4, 5). However, before either of the two can be used as such in clinical practice, the normal developmental course and its possible sources of variation must be defined. This requires the use of a prospective longitudinal study design (6). In the present study, we focused on the developmental course of various quantitative aspects of fetal body movements.Several authors have reported on the incidence of fetal body movements. However, because of the absence of a uniform definition of a body movement, and differences in study design (longitudinal or cross-sectional) and data analysis, the reported mean/median values and ranges of normality differ greatly among the various studies (7-16), as we have recently describ...

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“…This is consistent with other longitudinal studies (Sandman et al, 2013; ten Hof et al, 2002) and not the result of lack of interest in earlier gestation, but of the capabilities of cardiography in maintaining adequate signal detection of the fetal heart for prolonged periods of time. For example, the fetal heart rate error rejection declines precipitously between 20 and 24 weeks, from 16% to 8.5% in our original cohort (DiPietro et al, 1996b) and from 11% to 7% in Cohort I of this report (unpublished data), despite the use of ultrasound to guide transducer placement by a highly experienced clinician.…”

“…Some studies report that the fetus becomes less active as term approaches (Roodenburg et al, 1991; ten Hof et al, 2002), although others fail to show changes during the third trimester (Manning, Platt, & Sipos, 1979; Patrick, Campbell, Carmichael, & Probert, 1982). Differences in how fetal movement is defined across studies make comparisons difficult (ten Hof et al, 1999) as can inherent attributes of motor activity.…”

Effects of docosahexaenoic acid supplementation during pregnancy on fetal heart rate and variability: A randomized clinical trial

“…States 1F (calm, non-REM) and 3F (calm wakefulness) associated with absent, sporadic or short-lasting HR accelerations were classified as quiet states. States 2F (active REM) and 4F (active wakefulness) with frequent, long-lasting accelerations that return to the baseline were classified as active states [22]. If state determination differed between personnel, a third opinion was sought and consensus was reached.…”

Fetal heart rate and motor activity associations with maternal organochlorine levels: results of an exploratory study

“…Describing developmental trends in motor activity can be challenging due to variation in movement criteria across studies 29 . In general, the number of movements declines slightly during the second half of gestation while duration and amplitude or vigor increases 25, 26, 30, 31 . There is wide inter-individual variability in fetal motor activity 32 and although evidence is limited, more active fetuses tend to become more active infants 21, 33, 34 and young children 35 .…”

“…Greater inhibitory control of motor activity is considered to be a hallmark of early child development 24 . Fetal motor activity is not as readily measured or consistently defined as fetal heart parameters, but also develops in predictable ways 15, 25, 26 . Spontaneously generated movements can be observed in the late embryonic/early fetal period 27 and over gestation motor activity patterns coalesce into bouts of rest and activity that correspond to heart rate changes 28 .…”