What Is the Birth Canal?
During a vaginal delivery, your baby passes through your dilated cervix and pelvis into the world. For some babies, this trip through the “birth canal” doesn’t go smoothly. Birth canal issues can make vaginal delivery difficult for women. Early recognition of these issues can help you deliver your baby safely.
During the labor process, the baby’s head will tilt down toward the mother’s pelvis. The head will push on the birth canal, which encourages the cervix to enlarge. Ideally, the baby’s face will be turned toward the mother’s back. This promotes the safest passage for a baby through the birth canal.
However, there are several directions a baby can be turned that aren’t safe or ideal for delivery. These include:
- face presentation, where the baby’s neck is hyperextended
- breech presentation, where the baby’s bottom is first
- shoulder presentation, where the baby is curled against the mom’s pelvis
Your doctor can try redirecting your baby’s position to ensure a safer trip down the birth canal. If successful, your baby’s head will appear in the birth canal. Once your baby’s head has passed, your doctor will gently turn your baby’s shoulders to help them move past the pelvis. After this, your baby’s abdomen, pelvis, and legs will pass through. Your baby will then be ready for you to welcome them into the world.
If your doctor can’t redirect the baby, they may perform a cesarean delivery to ensure a safe delivery.
Remaining in the birth canal for too long can be harmful for a baby. The contractions can compress their head, causing delivery complications. Birth canal issues can result in prolonged labor or failure for labor to progress. Prolonged labor is when labor lasts longer than 20 hours for a first-time mother and longer than 14 hours for a woman who’s given birth before.
Nurses and doctors will monitor your baby’s progress through the birth canal during labor. This includes monitoring fetal heart rate and your contractions during delivery. Your doctor may recommend interventions if your baby’s heart rate indicates they’re in distress. These interventions can include a cesarean delivery or medications to speed up your labor.
Causes of birth canal issues can include:
- shoulder dystocia: This occurs when the baby’s shoulders cannot pass through the birth canal, but their head has already passed through. This condition can be difficult to predict because not all large babies have this problem.
- large baby: Some babies are simply too large to fit through their mother’s birth canal.
- abnormal presentation: Ideally, the baby should come head first, with the face looking toward the mother’s back. Any other presentations make it hard for the baby to pass through the birth canal.
- pelvic abnormalities: Some women have a pelvis that causes the baby to turn when approaching the birth canal. Or the pelvis can be too narrow to deliver the baby. Your doctor will assess your pelvis early in the pregnancy to check if you’re at risk for birth canal issues.
- uterine fibroids: Fibroids are non-cancerous growths in the uterus that can block a women’s birth canal. As a result, a cesarean delivery may be necessary.
Talk to your doctor about any concerns you have for your pregnancy. You should also let them know if you have any of these abnormalities, or have given birth to a baby after birth canal issues.
Your doctor can perform an ultrasound to check if your baby is at risk for birth canal issues. During the ultrasound, your doctor may determine:
- if your baby is growing too large to pass through the birth canal
- the position of your baby
- how large your baby’s head may be
However, some birth canal issues cannot be identified until a woman is in labor and the labor fails to progress.
A cesarean delivery is a common method to treat birth canal issues. According to the American Pregnancy Association, one-third of all cesarean deliveries are performed because of failure to progress in labor.
Your doctor may recommend changing positions if your baby’s positioning is causing a birth canal issue. This could include lying on your side, walking, or squatting to help your child rotate in the birth canal.
Birth canal issues may lead to a cesarean delivery. Other complications that can occur include:
- Erb’s palsy: This often occurs when a baby’s neck is stretched too far during delivery. It also happens when a baby’s shoulders cannot pass through the birth canal. This can result in weakness and affected movement in one arm. In rare cases, some babies experience paralysis in the affected arm.
- laryngeal nerve injury: Your baby can experience a vocal cord injury if their head becomes flexed or rotated during delivery. These can cause your baby to have a hoarse cry or have difficulty swallowing. These injuries often resolve in one to two months.
- bone fracture: Sometimes trauma through the birth canal can cause a fracture, or break, in a baby’s bone. The broken bone can occur in the clavicle or other areas, such as a shoulder or leg. Most of these will heal with time.
In extremely rare instances, trauma from birth canal issues can lead to fetal death.
Make sure you regularly attend prenatal checkups, and receive careful monitoring during your delivery. This will help you and your doctor make safe choices for your baby. Birth canal issues may prevent you from delivering your baby through your vagina. A cesarean delivery can help you deliver your baby without any more complications.