Which of the following is the second most common facial birth defect?

The second most common facial birth defect is cleft palate. Cleft lip is typically recognized as the most frequent facial birth defect, leading to cleft palate being the second most common. Clefts occur when there is a failure of fusion in the structures that form the lip and the upper jaw, resulting in various forms of clefts that can impact both function and appearance.

Cleft palate occurs when there is an opening in the roof of the mouth due to the palatine processes of the maxilla not fusing properly during embryonic development. This condition can often be associated with other congenital anomalies, but its prevalence solidifies its role as a significant and common facial birth defect behind cleft lip.

Hemifacial microsomia and Treacher Collins syndrome are also congenital conditions that affect the face but are less common compared to cleft lip and cleft palate. Hemifacial microsomia involves underdevelopment of one side of the face, while Treacher Collins syndrome affects facial bone development more broadly and can include features like down-slanting eyes and hearing loss, but these occur with lower frequency than the cleft conditions.