Normal Patterns of Fetal Activity in the Third Trimester

Abstract

Summary The incidence and frequency of fetal respiratory movements (FRM) and fetal trunk movements (FTM) were measured in 21 normal pregnancies between 28 and 39 weeks gestation. Fetal activity was assessed with a real‐time ultrasound scanner and all observed movements were punched directly onto computer tape. Recordings were made for one hour in three over a 24 hour period, providing a total of 168 hours for analysis. The overall mean percentage incidence of FRM was 31 per cent at a mean breathing rate of 43 breaths/minute. The mean percentage incidence of FRM during the day (0800–1759 hours) was 37 per cent. The overall mean percentage incidence of FTM was 18 per cent with a mean of 29 moves per 30 minute observation period. The mean percentage incidence of FTM during the day (0800–1759 hours) was 16 per cent. There was a well‐defined circadian variation in fetal activity with FRM peaking between 1900 and 2200 hours, and FTM between 2200 and 0100 hours. There was considerable variation in the amount of FRM and FTM recorded from hour to hour. Total fetal activity rarely fell below 10 per cent in any one recording period and this measurement may be a more useful clinical test of fetal well‐being than FRM or FTM alone.

Activity patterns assessed throughout 24-hour recordings in preterm and near term infants

“…Differences between night and day in preterm infants can only be inferred from data provided by Mirmiran and Kok (1991) and Glotzbach, Edgar, and Ariagno (1995); in these studies a temporal (circadian like) modulation of motility was extremely rare. An increase, similar to ours, of motor activity during the night with respect to the day has been observed in the fetus by Patrick et al (1982) and by Roberts, Little, and Cooper (1979). This day±night difference in the fetus has been explained as being due to maternal in¯uences (Arduini et al, 1986), even if the mechanisms involved are still obscure (de Vries et al, 1987).…”

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

“…The reason for the high intra-and interfetal variation is not clear at present, but could not be attributed to differences in recording time during daytime. In the literature, however, diurnal rhythms have been found to influence fetal activity (8,12,52,53). This seeming discrepancy could be explained by the fact that we standardized for the time of recording within each fetus and that all recordings were performed during daytime, whereas fetuses have been described to be most active between 2100 and 0100 h (8,52).…”

“…In the literature, however, diurnal rhythms have been found to influence fetal activity (8,12,52,53). This seeming discrepancy could be explained by the fact that we standardized for the time of recording within each fetus and that all recordings were performed during daytime, whereas fetuses have been described to be most active between 2100 and 0100 h (8,52). A possible effect of ultradian rhythms was unlikely as the intrafetal variance was still 56% (range 37-62%) for the percentage incidence of movements during FHRP B.…”

Development of Human Fetal Behavior: A Review

“…They have been defined as downward movement of the diaphragm with outward movement of ab dominal contents and inward displacement of the thorax [60], It is now well established that breathing is a normal feature of fetal life which is episodic in nature, with circadian and ultradian biological rhythms [30,[61][62][63][64] and a tendency to be stimulated by glucose [65][66][67][68] and carbon dioxide [69,70] and inhibited by hypoxia [61,71,72], Much data have been accumulated on fetal breathing in chronically instrumented fetal animal prepa rations, especially the fetal Iamb. With the development of noninvasive technology for fetal observation, interest in fetal breathing extended to its use as a parameter of well being in the human fetus [73][74][75][76][77].…”