Risk factors for shoulder dystocia can be divided into three general categories:

Preconceptual  (before pregnancy)

Anterpartum  (during pregnancy)

Intrapartum  (during labor and delivery)

Preconceptual risk factors for shoulder dystocia include:

  1. Previous shoulder dystocia

One of the most accurate predictors of shoulder dystocia is that of a previous incidence.  The anatomy of a woman’s pelvis does not change in between pregnancies; therefore, second and subsequent babies are most likely to be larger than the first (or previous) babies.

  1. Maternal obesity

A mother’s weight has proved to be a significant risk factor with shoulder dystocia.

  1. Maternal age

There have been some studies claiming that maternal age can be a risk factor for shoulder dystocia.

Antepartum risk factors for shoulder dystocia

  1. Macrosomia

Macrosomia is defined as an abnormally large baby and there have been various cutoff points used to define it as being 4000g, 4500g and as much as 5000g.  One of the most important factors about macrosomia is the difference in the rate of growth of the fetal head, chest and trunk as gestation progresses in both, babies of diabetic and non-diabetic mothers.  Until 36-38 weeks, the fetal head generally remains larger than the trunk of the baby’s body.  Between 36-40 week, the relative growth of the abdomen, chest and shoulders begins to exceed that of the fetal head.  This is particularly the case in babies of diabetic mothers where the glucose substrate levels are higher in both the mother and fetus.  In prolonged gestation, babies of diabetic mothers and the size of a baby’s trunk is likely to increase, thereby increasing its chances of shoulder dystocia.

While macrosomia is not the most significant risk factor for shoulder dystocia, it has been most studied and most often proposed as a potential target employed in hopes of reducing the number of shoulder dystocia deliveries.  Some authors claim that no other risk factor has any independent predictive value for the occurrence of shoulder dystocia.  However, Acker (1985) found that babies weighing over 4500g (9.92 lbs.) experienced shoulder dystocia 22.6% of the time.  Moreover, more than 70% of all shoulder dystocias in his study occurred in infants weighting more than 4000g (8.82 lbs.)

  1. Diabetes

The factor most closely associated with shoulder dystocia is maternal diabetes in pregnancy.  In Al-Najashi’s study (1989), the rate of shoulder dystocia in babies weighing over 4000g born of diabetic mothers was 15.7%.  Babies born to non-diabetic mothers had a shoulder dystocia rate of 1.6%.

Intrapartum risk factors

  1. Instrumental delivery

Several studies have shown that labors ending in instrumental vaginal deliveries, utilizing forceps or vacuum, show a higher rate of shoulder dystocia in each fetal weight group.

  1. Experience of the deliverer

Unsurprisingly, more experienced practitioners have had better outcomes in these situations by primarily due to them performing more deliveries.  The safe resolution of a shoulder dystocia involves specific obstetrical maneuvers.  Due to the fact that shoulder dystocias occur relatively infrequently, the more deliveries a doctor has done the more shoulder dystocias the doctor has presumably encountered and successfully resolved.

  1. Labor abnormalities

There have been studies that show a higher incidence of shoulder dystocia in labors in which the second stage of labor is prolonged.

Treatment Options

The majority of brachial plexus injuries will resolve over the course of several months to a year.  Physical therapy is usually utilized within weeks of birth to help strengthen the muscles of those whose nerve supply has been damaged.

For injuries that are permanent in nature, there are two modes of therapy:

  1. Physical therapy can strengthen muscles where partial nerve motor supply has been affected to strengthen the surrounding muscles to compensate for functional loss and improve the range of motion of the affected shoulder, arm, elbow and/or hand.
  2. Surgical therapy involving nerve grafting or muscle transposition may be performed.  However, there is controversy regarding the effectiveness of such surgical procedures in improving the outcome of those with brachial plexus injuries.  Additionally, orthopedic and neurosurgeons around the country, who perform this type of surgery, frequently report various degrees of improvement in many of their patients.  Others in the field refute these claims and feel there is little or no benefit to such a surgery.

If your or a loved one’s baby has experienced a shoulder dystocia injury and you feel it may have been prevented, contact the Shelton Law Group at (888) 761-7204 or (502) 409-6460, or visit www.robsheltonlaw.com.  We will work with you to ascertain whether you have a medical negligence claim resulting from a failure to provide appropriate preventative measures and subsequent treatment.