ABSTRACT
In the human fetus and neonate, there is now substantial evidence for the existence of cyclic fluctuations in spontaneous motor activity (CM, Fig. 10.1), comprised of general movements of the limbs, trunk, and head, on a time scale of minutes (Robertson, 1990). The cyclic fluctuations emerge before midgestation, perhaps as early as the 12th postmenstrual week (de Vries, Visser, & Prechtl, 1982). The quantitative properties of CM are remarkably stable during the second half of gestation, and the physiologic changes at birth do not appear to induce changes in CM (Robertson, 1985, 1987). However, fetal CM is influenced by maternal diabetes (Robertson & Dierker, 1986; Robertson, Klugewicz, & Lalley, 1992), yet returns to normal by the end of gestation and remains normal after birth, even in those infants with clinical evidence of having been exposed to an abnormal metabolic environment in utero (Robertson, 1988). CM persists for at least the first 4 postnatal months; during active sleep it remains nearly identical to fetal CM. However, awake CM becomes somewhat weaker and less predictable, as more complex fluctuations emerge at higher frequencies (Robertson, 1993b). Cyclic fetal motor activity (CM). Top: The total duration of spontaneous fetal movement in successive 5-sec intervals in a human fetus at 240 postmenstrual days of gestation. Fetal movement was detected by two strain gauges on the mother's abdomen. The pregnancy was complicated by maternal diabetes (classc). The fetus was subsequently born without complications at 270 days of gestation but was large for gestational age with a birth weight of 4.41 kg. Bottom: The number of movements observed in successive 5-sec intervals in a rat fetus on day 20 of gestation. The fetus was observed undisturbed in a warm saline bath following delivery from the uterus and amniotic sac, with fetal-placental-uterine connections intact (Smotherman et al., 1988). Both time series were smoothed with a 15-sec moving average. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203773628/0bf542be-1f06-462e-a902-045fbdeaf833/content/fig10_1_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>
