What it is

The RCOG's definition is precise: shoulder dystocia is "when the baby's head has been born but one of the shoulders becomes stuck behind the mother's pubic bone, delaying the birth of the baby's body". Extra help is usually needed to release the shoulder, and "in the majority of cases, the baby will be born promptly and safely".

How common, and in whom

The RCOG's figure is "about one in 150 (0.7%) vaginal births". That is the denominator to hold onto: vaginal births, not all births.

It is more likely if you have had shoulder dystocia before, if you have diabetes, if your body mass index is 30 or more, if your labour is induced, if you have a long labour, or if you have an assisted vaginal birth with forceps or ventouse. The RCOG's patient information on a raised BMI names shoulder dystocia among the complications that are more likely, "particularly if your BMI is 40 or more". ACOG lists a large baby among the pregnancy risks associated with obesity in the United States.

Two of the RCOG's statements about size cut against what most people assume. Shoulder dystocia is more likely with large babies, "but nevertheless there is no difficulty delivering the shoulders in the majority of babies over 4.5 kg (10 lb)". And: "Half of all instances of shoulder dystocia occur in babies weighing less than 4 kg (about 9 lb)."

Can it be predicted or prevented?

The RCOG's answer to both is essentially no. "Shoulder dystocia usually occurs unexpectedly during childbirth and most of the time it is not possible to predict when it will happen." Scans are not the answer either: "Ultrasound scans are not good at telling whether you are likely to have a large baby and therefore they are not recommended for predicting shoulder dystocia, if you have no other risk factors."

The one exception the RCOG names is diabetes. If you have diabetes or have developed it in pregnancy, you will usually be offered early induction or a planned caesarean, and this "will reduce the risk of shoulder dystocia". Without diabetes, the RCOG is explicit that "early induction of labour does not prevent shoulder dystocia, even if your baby is suspected to be large. Caesarean section is also not routinely recommended in this situation."

What happens in the room

The RCOG describes it honestly, including the part that frightens people. "Your midwife will push the emergency bell and three or four members of staff, including obstetricians, midwives and a doctor for the baby (paediatrician), are likely to come into the delivery room to help. Because it happens so quickly and lots of people come into the room, it may be frightening for you and your birth partner."

The usual sequence:

You are asked to stop pushing.
You are repositioned — onto your back with your legs pushed outwards and up towards your chest. This is the McRoberts manoeuvre.
Someone presses on your abdomen just above the pubic bone to try to release the shoulder.
An episiotomy may be considered, to enlarge the vaginal opening.

The RCOG: "With these simple measures, the majority of babies are born safely."

If the shoulder is not released, either the obstetrician or midwife puts a hand into the vagina to free the shoulder, or you may be helped to roll onto all fours, "which can also help to release the shoulder". Once the shoulders are free the baby is born and a paediatrician examines them.

If you are not on a labour ward

The RCOG is reassuring about place of birth: "Wherever you give birth, your midwife is trained to deal with shoulder dystocia." If the simple measures and the all-fours position do not work, your midwife will call an ambulance to transfer you. If the baby is born first, your midwife may still suggest you both go to hospital to be checked.

In a pool, you will be asked to get out so the midwife can help you. NICE's intrapartum guideline lists obstetric emergencies among the events that trigger transfer to obstetric-led care, and asks that a member of the team be allocated to talk with you and your birth companions throughout an emergency.

What it can mean afterwards

For you: the RCOG says vaginal tears are more common after shoulder dystocia "and may extend to the back passage", and heavier bleeding than normal after birth is also more common, sometimes needing additional treatment or a blood transfusion.

For the baby: "About one in ten (10%) babies who have shoulder dystocia will have some stretching of the nerves in the neck, called brachial plexus injury (BPI), which may cause loss of movement to the arm. The most common type of BPI is called Erb's palsy. It is usually temporary and movement will return within hours or days. Permanent damage is rare." The RCOG adds a point that gets lost in litigation coverage: BPI can occur without shoulder dystocia, and can occur in babies born by caesarean.

Fractures of the baby's arm or shoulder can happen and, in the RCOG's words, "in the majority of cases, these heal extremely well". The RCOG does not soften the rarest outcome either: "Even with the best care, in a very few cases, a baby can suffer brain damage if he or she did not get enough oxygen because the delivery was delayed."

Next time

The RCOG's figure for recurrence is "around one in ten women will have shoulder dystocia again in a future pregnancy". Its advice is not a rule but a set of considerations: a vaginal birth may suit you if the shoulders were released easily, the baby was fine and you have no other risk factors; a planned caesarean may suit you if it was difficult, the baby was injured, or "the experience has affected you and your family".

That last clause is doing real work. How the birth affected you is, in the RCOG's own text, a legitimate reason to choose differently next time.

Talking about it

The RCOG asks teams to talk to you about what happened at the time, and says that "if you wish to talk at a later date about your experience, ask to talk to your obstetrician, midwife, health visitor and/or GP". A shoulder dystocia is fast, crowded and often only half-remembered, which makes it one of the clearest reasons to ask for a birth debrief later.

This RCOG patient information was published in March 2013 and is based on its 2012 guideline for clinicians. It remains the RCOG's current public leaflet on the subject at the time of writing.

Shoulder Dystocia