Fetus yawning in utero
Citation, DOI, disclosures and case data
Routine obstetric scan for anomaly, placentation, presentation and biophysical profile score in a thirty year old.
Sagittal fetal face reveals (by chance) the fetus widely opening the mouth followed by a quick closure of the upper and the lower jaws that lingers for approximately 5 seconds with a simultaneous backward movement of the head and anterior chest forward movement. The tongue slightly draws back into the bucal cavity and relatively remains static during this momentous phenomenon
Yawning is a neurobehavioral pattern considered as an indicator of the nervous system development and has been described as a paroxysmic cycle characterized by a standard cascade of movements over 5 -10 seconds period during which, the fetal mouth (previously closed) opens widely for 4-6 seconds with simultaneous retraction of the tongue followed by a quick closure combined with retroflexion of the head and sometimes elevation of the arms (pandiculation) 1,2. Most literature posits that this harmonious sequence starkly differs from fetal swallowing which is brief and occasionally is repetitive.
In this presentation (in a healthy fetus at 31 weeks gestation with normal obstetrics parameters and morphology) the action was chanced just once and never repeated itself during the entire scan process which phenomenaly is characteristic of fetal yawning.