Shoulder presentation and delivery

Babies can enter this world through one of two ways, either by means of a vaginal birth or by a C-section. Either way, the aim is to safely give birth to a healthy baby. Vaginal delivery is the best alternative to bring your child into this world. No doubt about it. However, if there are any safety concerns  about  the health of the mother or the child, the doctor will opt a C-section

Generally, once you get into the 30th week of your pregnancy, the fetus starts to turn to the head down position, getting ready to be delivered. By the gestation reaches 35 weeks, the fetus moves into the position to come out of the mother's womb. This position, which the fetus attains has an important role in determines how easy the delivery will be (or rather how difficult), and also the chances of complication during the labor.

This is the typical position of a fetus during a vaginal delivery:

  • Head enters the birth canal fist (head down)
  • The baby's face will be faced towards the mother's spine
  • The face and body of the baby will tilt towards either right or left side
  • The chin and neck will bend towards the chest
  • Arms will be folded crosswise to the chest.

Any positions deviated from this is counted as atypical. The more the deviation the more will be the complications of the delivery. Sometimes, unexpected deviation happens during labor just before the fetus enters the birth canal. One of such rare, but a complicated instance that can be fatal for both mother and child (if not properly taken care) is shoulder presentation, during which the normal delivery becomes almost impossible.

What is shoulder presentation?

Shoulder presentation refers to an abnormally positioned fetus at the time of delivery. Here, the fetus lies crosswise so that its vertebral column lies at right angles to the maternal spine. Therefore, instead of the head,  the part that enters the birth canal will be the baby's trunk or shoulder or an arm.

The doctor tries for a vaginal birth, even there is some significant deviation from the normal position. But for that, the baby's head, or buttock, or feet should enter the birth first. Hence, the vaginal birth will be will be definitely unthinkable for shoulder presentation and the mother without any doubt,  has to undergo a C-section.

What are the causes of shoulder presentation?

Shoulder presentation can happen as a result of either maternal or fetal factor.

Lax  uterine and abdominal muscle:

As a result of numerous previous pregnancies, or a previous pregnancy with twins, the abdominal and uterine muscles can become unusually relaxed. This will bring down its capability to hold the baby in normal position. This failure of the uterine muscle can lead to shoulder presentation.

Contracted pelvis:

An unusually tapered pelvis can bring about shoulder presentation.

Overly expanded uterus:

The Overly expanded uterus can lead to shoulder presentation. An excessive amount of amniotic fluid(polyhydramnios),  multiple pregnancies, big baby, etc.  can result in an overly expanded uterus. This condition will provide more room for the fetus to move freely, thereby, increasing the chances of shoulder presentation.

 Uterine abnormalities:

Uterine abnormalities such as fibroid uterus, sub-septate uterus, in which, the uterine cavity is divided by an incomplete longitudinal septum, bicornuate uterus, in which, instead of the normal pear shape, the uterus appears like two horns separated by a septum, can bring about the shoulder presentation.

Placenta Previa:

Placenta Previa is a condition in which the placenta partially or wholly blocks the neck of the uterus and prevents the head of the fetus from entering the pelvic brim.

Intrauterine fetal death:

When the fetus dies inside the uterus before delivery the muscle tone of the fetus collapse (macerated fetus) which make the fetus fall into the lower portion of the uterus diagonally.

What are the possible complications of shoulder presentation?

A shoulder presentation means the baby cannot be delivered through the vagina. Once the woman already entered labor, the complication of the shoulder presentation increases significantly.  It can lead to,

Fetal hypoxia and death:

Fetal hypoxia refers to a condition in which the oxygen supply is hindered and the fetus encounter lack of oxygen. Delayed C-section can end up in death of the fetus

Cord prolapse

Here, the umbilical cord comes out of the uterus before the fetus. This can decrease considerably or even stop the oxygen and blood flow to your baby. Hereby, the heart rate and blood pressure of the fetus is adversely affected. It can also lead to brain damage to the fetus.

Obstructed labor:

Obstructed labor is a condition in which, in spite of the uterine contractions, the baby is not able to advance to the birth canal. An ignored obstructed labor is the major cause of the maternal and fetal death.

Ruptured uterus:

Uterine rupture, obviously, is a life-threatening event for both mother and child. Shoulder presentation increases the chances of uterine rupture.

Distress  to prolapsed arm:

The arm that prolapses through the birth canal has a higher chance to undergo trauma. This trauma can have a lifelong impact on that hand.

How is shoulder presentation diagnosed?

  • The uterus appearing wider from side to side is the first indication of shoulder presentation.
  • The fundal height appears less as the fundus of the uterus is neither occupied by the head nor by the buttock of the baby.
  • The mother will feel the head of the baby on the side of the abdomen.
  • A prolapsed arm confirms shoulder presentation.