Fetal yawning.

Incidental fetal yawning movements can rarely be observed during real-time ultrasonographic examination. In this report we document repetitive fetal yawning movements in a 27-week fetus over a 7-min period. Each episode lasted for 4-6 s, and the intervals between them varied from 21 to 195 s. This case demonstrated that fetal yawning, a complex involuntary behavioral reflex, is present in its full extent during the second half of pregnancy.