PubMed1982
A literature review reports the results of investigations about fetal intrauterine activity. Different methods of observation are demonstrated and discussed. The results indicate that real-time-ultrasound is an accurate method for observation of fetal movements. Different patterns are identified: 1. Fetal body and extremity movements Development of fetal activity in early pregnancy is looked at as a process of maturation associated with fetal cerebral function. After 12 weeks of pregnancy typical patterns are established and seen also in the following weeks. Different results are reported about frequency of fetal movements related to duration of pregnancy. A circadian rhythm seems to be associated with a peak in activity between 2100 and 0100 hours, although fetal activity is altered by a variety of drugs and external stimuli. The proportion of pathological foetal movements in early pregnancy seems higher in patients who aborted. There are findings in later pregnancy, which report good fetal outcome, if daily fetal movement recording is greater than 10 movements for 12 hours. 2. Fetal breathing movements are recognized as being normally present, but episodic, shallow and variable in rate and regularity. There is a great variability in the percentage of time fetuses spend making breathing movements (mean 30-50% per hour; range 0-80%). Under physiological conditions there is a circadian rhythm concomitant with changes in fetal low-voltage electrocortical activity. The activation of fetal breathing occurs mainly during rapid-eye-movement-sleep, but the physiologic control of the activation has not been identified. Apnea, frequency, variability and amplitude of breathing, continuous breathing or gasping are described, but positive identification of abnormal pattern is not achieved. Several factors affecting fetal breathing movements have been described, their physiologic significance and control and their clinical relevance remain to be clearly elucidated. 3. Total fetal activity Fetal biophysical variables such as tone, breathing, body and extremity movements and heart rate reactivity are initiated and regulated by the fetal central nervous system, and as such, the presence of a given variable is indirect evidence of a functioning and intact central nervous system. These variable could be depressed by hypoxemia or other factors. Data in literature suggest that combined fetal biophysical testing is a more accurate method of antepartum fetal evaluation than any single method.