Fetal mustache in early pregnancy

Objective. The aim of this study was to determine the incidence in an unselected population of a rod-like structure on the fetal upper lip (called a 'mustache') which we had previously observed as an incidental finding. A secondary aim was to determine whether this was associated with any abnormalities or abnormal outcomes. Design. Prospective non-randomized study. Subjects. Three thousand consecutive fetuses from an un-selected population were scanned by one sonologist. Method. Transvaginal ultrasound examinations were performed at 14-16 weeks' gestation. Repeat sonographic examinations were performed at 20-22 weeks' gestation in cases where a mustache was detected, and these neonates were examined by a pediatrician after delivery. Results. Seven of 3000 fetuses had a mustache-like structure on the upper lip. The 'mustache' disappeared later in gestation. No anomaly of the upper lip was detected after birth in these fetuses. Conclusion. A mustache-like structure on the fetal upper lip in early pregnancy probably represents a normal variant of lip development. It is likely to represent a delay in the normal process of lip fusion during embryonic life.