Face presentation is an uncommon variation of fetal position during childbirth, where the baby’s face, rather than the crown of the head, leads the way through the birth canal. This type of fetal malpresentation deviates from the typical head-first position, introducing complexities to labor and delivery.
Understanding Face Presentation
In a face presentation, the baby’s head is hyperextended, meaning the neck is bent backward so that the back of the head touches the baby’s upper back. The presenting part becomes the face, specifically the area between the orbital ridges and the chin. This differs from the usual vertex presentation where the baby’s chin is tucked to its chest, allowing the smallest diameter of the head to pass first.
The orientation of the baby’s chin, or mentum, relative to the mother’s pelvis further classifies face presentations. In a mentum anterior (MA) position, the baby’s chin faces the mother’s front side, towards her pubic bone. This alignment often allows for vaginal delivery. Conversely, a mentum posterior (MP) position means the chin faces the mother’s back, a configuration that makes vaginal delivery difficult or impossible. A mentum transverse (MT) position occurs when the chin is facing the side of the birth canal.
Factors Influencing Face Presentation
Several conditions can contribute to a baby presenting in a face position, often preventing fetal head flexion or encouraging extension. Maternal pelvic abnormalities, such as a contracted pelvis or cephalopelvic disproportion (mismatch between baby’s head size and mother’s pelvis), can lead to face presentation. Fetal anomalies, including anencephaly, hydrocephalus, or neck masses, can physically impede head flexion.
Excessive amniotic fluid (polyhydramnios) allows the fetus more room for movement, potentially leading to unusual positions. Prematurity and very low birth weight can also be contributing factors, as smaller babies may have less muscle tone to maintain a flexed position. Grand multiparity (a mother who has given birth five or more times) can result in decreased uterine tone, which can increase the likelihood of malpresentation.
Detecting Face Presentation
Healthcare professionals identify face presentation during later pregnancy or, more commonly, during labor. Abdominal palpation, using Leopold’s maneuvers, might suggest an irregular fetal shape or an unusual head configuration. The fetal spine may feel curved in an ‘S’ shape.
A vaginal examination is a primary diagnostic tool as labor progresses and the cervix dilates. During this examination, the practitioner can feel distinctive facial landmarks such as the mouth, nose, chin, and orbital ridges. It is important to differentiate these features from those of a breech presentation, as both can involve soft tissues with an orifice. Ultrasound imaging provides definitive confirmation by clearly showing the hyperextended fetal neck and the position of the face.
Management and Delivery Considerations
Managing a face presentation requires careful assessment and individualized care, as the approach depends significantly on the chin’s position. If the baby is in a mentum anterior (chin forward) position, vaginal delivery is often possible. In these cases, contractions can help rotate the chin further anteriorly, allowing the head to flex and pass under the mother’s pubic bone. Approximately 73% of mentum anterior cases can deliver spontaneously.
However, if the baby’s chin is in a mentum posterior (chin backward) position, vaginal delivery is not feasible. In this alignment, the fetal neck is already maximally extended, and the head, neck, and shoulders would attempt to enter the pelvis simultaneously, presenting a diameter too large for the maternal pelvis. Persistent mentum posterior presentation is an indication for a Cesarean section. While some mentum posterior positions may spontaneously rotate to mentum anterior during labor, this occurs in only about 25-33% of cases.
Continuous electronic fetal heart rate monitoring is used for face presentations due to an increased risk of abnormal heart rate patterns and fetal distress. If labor is not progressing adequately or if there are signs of fetal compromise, a Cesarean section may be necessary. Manual attempts to rotate the baby or convert the presentation are not recommended due to risks of fetal and maternal injury, including spinal cord damage or uterine rupture. When a Cesarean section is performed, medical staff should be prepared for potential neonatal complications such as facial swelling or respiratory distress, which resolve within 24-48 hours.