Shoulder dystocia is a rare occurrence during labour, happening in about 0.5% or 1 in 200 births.
While there are risks factors for shoulder dystocia, it’s usually not predicted before labour has begun.
Shoulder dystocia can happen during c-section birth as well.
During normal labour, there can be a delay between the birth of the baby’s head and the body.
When shoulder dystocia occurs, the baby’s head is born and the body is unable to follow, as one or both of the shoulders have become caught inside the mother’s body.
Shoulder dystocia is a birth complication that requires immediate attention.
Fortunately, it’s a rare occurrence, but is it something you should be concerned about?
What Is Shoulder Dystocia?
During undisturbed labour, the mother instinctively moves into positions that help her baby to move into the best position for birth.
Once the cervix has opened, the baby enters the birth canal and must rotate through the pelvis in order to be born.
After the head has been born, the baby’s head and body will turn sideways. This usually allows the shoulders to pass under the pubic bone (found midway down under your belly button). Once the shoulders have passed through the rest of the body can be born.
In some circumstances the baby’s shoulders are unable to get past the pubic bone. This is called shoulder dystocia and is considered a medical emergency. The baby is unable to begin breathing until its body is born.
The longer the delay between the baby’s head and body being born, the greater the risk of asphyxia (oxygen deprivation).
What Are The Risk Factors?
It’s difficult to predict when shoulder dystocia will occur. There are a number of risk factors that increase the chances of shoulder dystocia occurring:
- Your baby is over 4.5kgs (macrosomia)
- You have gestational diabetes (increases the chance of a large baby)
- You have already experienced shoulder dystocia in a previous labour
- You are induced
- Ventouse or forceps are used
Research has shown that maternal weight is not necessarily a risk factor for shoulder dystocia, unless the mother has gestational diabetes and is more likely to be carrying a large baby. It is important for pregnant women to eat a low GI diet – ideally this starts before conception.
Read more about gesational diabetes facts and treatments.
Shoulder dystocia is most commonly linked to babies who are over 4.5kg. Care providers may predict a large baby and suggest induction before full term to avoid shoulder dystocia if the baby grows more before birth.
However, ultrasounds are not an accurate predictor of birth weight towards the end of pregnancy and at least half of all babies with shoulder dystocia are under 4kgs in weight.
An induction of labour can further complicate things by creating such strong, intense contractions that a baby is essentially forced into an awkward position.
Additionally, women who are induced are unable to move freely to cope with contractions, as they have an IV drip in place as well as a fetal monitoring belt keeping them on the bed.
The strong, painful contractions often lead women to requesting an epidural for pain relief. This usually means a reclining or semi sitting position, which restricts the pelvis movement necessary for the baby to rotate for birth.
What Happens When Shoulder Dystocia Occurs?
If shoulder dystocia occurs it’s very likely your care provider will call in assistance from other staff. This may include the obstetrician, other midwives and a paediatrician. Parents can find this extremely stressful especially if there is no clear explanation of the emergency.
If the mother has not had an epidural, her care providers will first focus on getting her into a new position to increase the pelvis size and if this doesn’t work, move the baby into a better position. Very rarely, if changing positions doesn’t work, care providers may opt to break the baby’s collarbone to free the shoulder.
In some cases more than one of the following techniques may tried in very quick succession.
- McRobert's Maneuver: most common technique, involves flexing the mother's legs toward her shoulders as she lies on her back. This opens up the pelvis allowing room for the baby’s shoulders to be born.
- Suprapubic Pressure: often used in conjunction with the above technique. Pressure is applied at the pubic bone to release the baby’s shoulder.
- Gaskin Maneuver: named after well-known midwife Ina May Gaskin, this technique involves moving the mother to an all fours position with her back arched. This widens the pelvic outlet.
- Woods Maneuver: also referred to as the corkscrew, the care provider places fingers inside the vagina onto the baby’s shoulder and pushing round and out.
- Rubin Maneuver: this technique is similar to the above. Two fingers are placed behind the baby's shoulder, pushing in the directions of the baby's eyes, to line up the shoulders.
- Zavanelli Maneuver: this technique is used only after other techniques have failed, as it’s associated with high risk to mother and baby. It involves pushing the baby's head back inside the vagina in preparation for a c-section.
C-section is usually the absolute last resort as it can take time to prepare. If it’s possible, the mother is given a general anaesthetic and the baby will be moved back up the birth canal, before being born through an incision to the uterus.
Is It Possible To Avoid Shoulder Dystocia?
It’s hard to predict which babies will have shoulder dystocia and it’s not something that can necessarily be prevented.
Being aware of optimal fetal positioning during pregnancy helps encourage your baby to settle into a good position in the lead up to birth. Your own physical health is also important – be aware of your body and pelvis and how they will open up and flex during labour.
Choose care providers who support and facilitate undisturbed birth. Trying to hurry labour along through the use of interventions, induction or coached pushing can contribute to babies being unable to get into the best position or put women in positions that restrict pelvic opening.
Discuss with your care provider what their expectation is around the birth of the baby’s head and body, and if their approach is hands on or hands off. If shoulder dystocia occurs, will your care provider want to immediately cut the cord, potentially depriving your baby of oxygen?
If you need or plan to have an epidural, ask your care provider about support to utilise positive movements and positions to increase your pelvis size. If this is not an option, consider hiring a doula who can provide you with non-medical physical and emotional support.
What Happens To Mother And Baby?
If shoulder dystocia occurs, there can be complications for both mother and baby.
Your baby may have brachial plexus injury. This means nerves in your baby’s neck have become stretched and may lose movement and feeling in the arm. In most cases, this is temporary and movement returns within hours or days after birth. Around 1 in 100 babies will have permanent damage and will go on to require physical therapy.
If the baby’s arm, shoulder or collarbone was broken, pain relief will be given. The bone usually heals quickly and without any long-term problems.
Very rarely, despite the best efforts of care providers to release the baby, oxygen deprivation can happen and cause brain damage or death.
The mother can also experience complications following shoulder dystocia. Vaginal tears are more likely to happen, including ones that involve muscle in the vaginal wall or toward the rectum. Severe bleeding (postpartum haemorrhage) happens in about 10% of women following shoulder dystocia.
Often women feel traumatised by their birth experience, and guilt that they may have caused harm to their baby. These emotions can have detrimental effects to the emotional health of the mother and may affect her experience of early parenting.
Will It Happen Again?
If you experience shoulder dystocia there is a 1 in 8 chance it will happen again.
It’s important you talk to your care provider about any possible risk factors that may have contributed to shoulder dystocia and if they can be avoided in future. If you had gestational diabetes in a previous pregnancy, talk with you care providers about ways to prevent or manage it in future pregnancies.
Some care providers will recommend an elective c-section for your next birth but there is currently no evidence to suggest this is the best option. It’s important to weigh all of the benefits and risks of a c-section versus a vaginal birth before making a decision.
Shoulder dystocia can occur during c-section and there are associated risks with the surgery itself. While there is a risk of shoulder dystocia occurring again, more often than not it doesn’t.
If you are experiencing trauma regarding your birth experience, seek the support of your care provider or maternal health nurse, or look up a birth trauma organisation in your area.