Brow presentation describes a fetal position when the baby’s head is extended back, with the forehead leading the way through the birth canal. The fetal head is midway between full flexion (vertex position) and hyperextension (face position) along a longitudinal axis. Because the diameter of the fetal head at this angle may be greater than that of the mother’s pelvic outlet, a cesarean section may be recommended.
What Causes Brow Presentation?
Brow presentation is the least common of fetal positions. The causes are generally similar to those causing the “face” position. The condition may be caused by premature rupture of membranes, increasing parity, or premature birth. It may also be caused by pelvic contractures or android pelvis, which is a pelvis with a wedge-shaped inlet and narrow anterior segment.
How is Brow Presentation Diagnosed?
Brow presentation is seldom detected until labor. Contractions of the uterus can put pressure on the baby, causing the baby to shift the position of the head. When the brow position is discovered before birth, it may be as a result of the caregiver noticing that the shape of the mother’s belly is unusual. The baby’s head may also seem to be high, or unengaged. If the medical professional suspects a brow presentation, an ultrasound will be ordered to confirm the condition. Malpresentations, such as brow presentation are usually more difficult to deliver or are not deliverable by natural means.