Correspondence

A Fetal Yawn?

N Engl J Med 1997; 336:1329-1331May 1, 1997

Article

To the Editor:

Regarding the interpretation of the Image in Clinical Medicine entitled “A Fetal Yawn” (Nov. 14 issue)1 showing an ultrasonogram in which a 34-week-old fetus is reported to be yawning, the literature fails to define yawning in a fetus, with the result that far too many interpretations of open mouths as yawns have been accepted.2,3 The range of variation includes, for example, a single, continuous opening of the mouth lasting three minutes2 and a set of five repetitive openings of the mouth for four to six seconds each.3 There is also a discrepancy in the use of the anatomical criterion of retraction of the tongue to characterize the fetal yawn,3 whereas in yawning adults, the tongue is extended.4 Furthermore, we question the validity of the claim that such a “rarely observed” event3 is not just a reflex related to the swallowing of amniotic fluid and prolonged by chance alone.

Finally, if the assessment is based on accepted models in adults, there is no physiologic reason why a fetus should yawn. Doppler studies during yawning have shown no hypoxia3; yawning confers no protection against atelectasis in a fluid-filled lung3; because infants with anencephaly have been shown to yawn,5 the action cannot be attributed to boredom; and if there is a need to yawn, the reported repetitive nature of the action appears to signify an inability to compensate for that need.

Brian McManus, M.S.
Patricia Devine, M.D.
Robert D. Brandstetter, M.D.
Sound Shore Medical Center of Westchester, New Rochelle, NY 10802

5 References

1. 1

   Egerman RS, Emerson DS. A fetal yawn. N Engl J Med 1996;335:1497-1497
   Full Text | Web of Science | Medline

2. 2

   Sherer DM, Smith SA, Abramowicz JS. Fetal yawning in utero at 20 weeks gestation. J Ultrasound Med 1991;10:68-68
   Web of Science | Medline

3. 3

   Sepulveda W, Mangiamarchi M. Fetal yawning. Ultrasound Obstet Gynecol 1995;5:57-59
   CrossRef | Web of Science | Medline

4. 4

   Aloe F. Yawning. Arq Neuropsiquiatr 1994;52:273-276
   CrossRef | Medline

5. 5

   Gamper E. Bau und Leistungen eines menschlichen Mittelhirnwesens (Arhinencephalic mit Encephalocele). Z Gesamte Neurol Psychiatr 1926;102:154-235
   CrossRef

Author/Editor Response

The authors reply:

To the Editor: Although we are surprised that the glimpse of a quiet, gentle act has provoked such a strong response, we recognize that reviewing a single static image may produce a skeptical response. Anyone involved with ultrasonography, however, recognizes that it is a dynamic method, and the real-time viewing of a yawn in process is much more compelling and less open to alternative interpretations. Limitations of publishing technology prevent us from sharing the full experience with readers.

Although fish,1 tortoises,2 and mammals yawn, we cannot explain why a human fetus would yawn. Behavior observed in utero, including breathing, yawning, and the startle response,3 serves as a continuum to the activity shown by a newborn infant. It is unlikely that on emerging from the birth canal, an infant undergoes a neuromuscular rewiring. The yawn, a rudimentary reflex, appears to have at best an obscure purpose, if any. Perhaps, as a paralinguistic communication,4 it signifies a time for group members to rest.5

Robert S. Egerman, M.D.
Donald S. Emerson, M.D.
University of Tennessee, Memphis, Memphis, TN 38103

5 References

1. 1

   Rasa OA. The causal factors and function of “yawning“ in Microspathadon chrysurus (Pisces: Pomacentridae). Behaviour 1971;39:39-57
   CrossRef | Web of Science | Medline

2. 2

   Luttengerger VF. Zum problem des gahnens bei reptilien. Z Tierpsychol 1975;37:113-137
   CrossRef | Medline

3. 3

   Sarinoglu C, Dell J, Mercer BM, Sibai BM. Fetal startle response observed under ultrasonography: a good predictor of a reassuring biophysical profile. Obstet Gynecol 1996;88:599-602
   CrossRef | Web of Science | Medline

4. 4

   Provine RR, Hamernik HB, Curchack BC. Yawning: relation to sleeping and stretching in humans. Ethology 1986;76:152-160
   CrossRef | Web of Science

5. 5

   Grier JW, Burk T. Biology of animal behavior. 2nd ed. Dubuque, Iowa: Wm. C. Brown, 1992.
   

Citing Articles (2)

Citing Articles

1. 1

   Asim Kurjak, Milan Stanojevic, Guillermo Azumendi, José M. Carrera. (2005) The potential of four-dimensional (4D) ultrasonography in the assessment of fetal awareness. Journal of Perinatal Medicine 33:1, 46-53
   CrossRef

2. 2

   E. O. Smith. (1999) Yawning: An evolutionary perspective. Human Evolution 14:3, 191-198
   CrossRef