Weeks 4 to 5: the building blocks appear
Five swellings of tissue, called the facial prominences, form around a central depression that will become the mouth. There is no recognisable face — just a frontonasal prominence above and paired maxillary and mandibular prominences at the sides. The eyes begin as optic vesicles on the sides of the head, not the front.
Weeks 6 to 7: migration and fusion
The mandibular prominences fuse in the midline to form the lower jaw and chin — the first recognisable facial structure. Nasal pits deepen into nostrils. The maxillary prominences grow forward and begin to fuse with the nasal prominences to form the upper lip. This fusion is the critical event: failure here produces cleft lip, and it happens between roughly weeks 5 and 7.
Weeks 8 to 9: a face you would recognise
The eyes migrate from the sides towards the front, which is what gives the human face its forward-facing binocular vision. Eyelids form and begin to cover the eyes. External ears develop from the neck region and move upward to their final position — which is why low-set ears are a marker clinicians look for. The palate begins to fuse from front to back, a process that continues to about week 12.
Weeks 10 to 12: refinement
The nose takes a defined shape with a bridge and tip. Tooth buds form beneath the gums. Eyelids fuse shut and stay closed until around week 26. Facial muscles begin to develop, and by week 12 brief reflexive movements — early frowning and mouth opening — can be seen. The palate completes fusion; failure at this stage causes cleft palate, which can occur with or without cleft lip.
Weeks 13 to 14 and beyond
All the structures are present, and from here it is growth and proportion. The profile becomes clear enough on ultrasound for the nasal bone to be measured at the 11 to 13 week scan, where absence or hypoplasia is one of the markers used in Down syndrome screening. Sucking and swallowing movements appear. By the second-trimester anomaly scan at 18 to 22 weeks, the lips and palate can be examined properly.
What influences facial development
- Folic acid — 400 micrograms daily from at least a month before conception reduces neural tube and facial cleft risk. Higher doses if you have had a previously affected pregnancy.
- Medicines — some anti-epileptics, isotretinoin and methotrexate are strongly associated with facial malformation. Review all medication before conceiving.
- Smoking and alcohol — both increase cleft risk, and alcohol affects the whole facial midline.
- Genetics — a family history of cleft lip or palate raises the risk and is worth mentioning at booking.
- Uncontrolled diabetes in the first trimester raises the risk of several structural anomalies.
What scans can and cannot show
The 11 to 13 week scan assesses the profile and nasal bone. The 18 to 22 week anomaly scan examines the lips and, less reliably, the palate — isolated cleft palate is frequently not detected before birth. A cleft found on scan is highly treatable with staged surgery and good long-term outcomes, and finding it early allows the surgical and feeding plan to be arranged in advance.