When it comes to how your baby is positioned in the birth canal, being head down is the best way to be. Other positions (known as “presentations” in the medical community) are known as malpresentations. Some malpresentations may make a vaginal delivery difficult or not possible at all. Breech presentations are well known malpresentations, but there are others you may not have heard about.
Face presentation. In a normal head down, or vertex, presentation, the top part of a baby’s head is lowest in the pelvis and birth canal. A face presentation, however, occurs when the baby’s face is the presenting part in the birth canal; this affects about 1 in 500 births. Your doctor or midwife will be able to feel the baby’s chin and usually the nose and eyes as well during a cervical exam in labor. This type of presentation can still lead to a vaginal delivery if the chin is in what we call the anterior position (imagine it this way: the back of the baby’s head is closest to the floor with the chin pointing up toward the ceiling). In fact, most face presentations with the chin in this position result in successful vaginal deliveries. If the chin is in a posterior position, or pointing toward the floor, a C-section is usually needed unless it spontaneously rotates into an anterior position.
The bottom line is that as long as Mom and baby are doing well, labor should be allowed to continue until the cervix stops dilating or it becomes obvious the baby is not going to rotate or come down farther in the pelvis, at which time a C-section would be needed.
Brow presentation. This presentation occurs when a baby is head down, but the baby’s chin is not tucked near the neck in the normal way. This leads to abnormal neck extension. During a cervical exam, your doctor will not feel the top of the baby’s skull but rather the frontal bones, which are just above the baby’s eyebrows. This happens on average in about 1 in 1,500 deliveries. Many times a baby will start out this way in early labor, only to flex later on and get into the normal presentation as labor progresses. If a brow presentation persists, though, fewer than 50 percent of moms will deliver vaginally. This is because the way the head is fitting into the pelvis is larger than a baby in the normal vertex presentation.
Compound presentation. This refers to whenever something is fitting into the birth canal along with the baby’s head. Most commonly this is the hand, and many an obstetrician and midwife have felt a little hand squeezing their finger during a cervical check! This happens in about 1 in 377 to 1,213 deliveries. Labor should be allowed to continue, as up to 75 percent of these will have successful vaginal deliveries. Some spontaneously resolve (for example, the arm will retract as the baby goes lower into the pelvis), while others just deliver with the hand alongside the head. A slightly higher risk of cord prolapse exists (where the umbilical cord comes into the birth canal ahead of the baby), which is an obstetrical emergency, but this increased risk is not a reason to automatically proceed with a C-section.
- Gabbe SG et al
- Obstetrics: Normal and Problem Pregnancies
- 5th ed
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