Development of human fetal behavior: a review.
Most of the movements described during the course of gestation have already emerged before 16 weeks, and the presence of diurnal variation in human fetal behavior has been demonstrated from as early as 20 weeks gestation. Up to 26 weeks quiet intervals rarely exceed 5 min. After this age quiet intervals progressively increase in duration so that behavior appears cyclically rather than randomly distributed. Increasing linkage of the state variables results in identifiable fetal behavioral states from around 36 weeks. During the last trimester fetal activities are cycle- or state-dependent, so that prolonged, and often repeated, recording of behavior is necessary before any sinister conclusions can be drawn.
Pillai
M
M
University Department of Obstetrics, Bristol Maternity Hospital, UK.
James
D
D
D002940:Circadian Rhythm; D005314:Embryonic and Fetal Development / Q000502:physiology*; D005260:Female; D005324:Fetal Movement / Q000502:physiology*; D005333:Fetus / Q000502:physiology*; D006340:Heart Rate, Fetal; D006801:Humans; D011247:Pregnancy; D012119:Respiration