Obstetricians and sonographers must keep careful track of the baby’s growth throughout the pregnancy.  A baby who is developing too slowly or growing too quickly may need intervention in order to prevent serious medical complications.  The medical term for a baby who is larger than she should be is macrosomia, also known as big baby syndrome.

Macrosomia:  Technical Definition

A baby is technically “large for gestational age” when her estimated fetal weight is greater than the 90th percentile.  That analysis is useful in determining macrosomia, but it does not go far enough.  Macrosomia is a high risk pregnancy situation, and the definition used by some obstetricians, including the American College of Obstetricians and Gynecologists (ACOG) is a birth weight greater than 4,500 grams (9 lbs., 15 oz.).  Others define it as a birth weight greater than 4,000 grams (8 lbs., 13 oz.).

Identification of Macrosomia

There are several warning signs that should put careful obstetricians on notice that a baby may be macrosomic:

    • Pre-pregnancy diabetes
    • Obese mother (BMI > 30, or over 198 lbs.)
    • Rapid/excessive pregnancy weight gain
    • Prior delivery of a “large for gestational age” baby or macrosomic baby
    • Post-term pregnancies (those that go beyond 42 weeks)
    • Male baby

When any of these warning signs are present, obstetricians should check to see if macrosomia is a true concern.  Doctors can check the baby’s size by pushing on the mother’s stomach using a technique known as the Leopold’s maneuver.  If large enough, an ultrasound will be used to determine the baby’s size, though these scans may be off by as much as fifteen percent.  Obstetricians and sonographers should double-check the date of conception to ensure an accurate calculation.

Treatment of Suspected Macrosomia

The underlying cause of macrosomia frequently must be managed, particularly in the case of diabetes.  Obese women should be instructed to gain less weight, and may require referral to a dietician or nutritionist.

Some doctors choose a cesarean section or induction for babies who are large for gestational age (before they become macrosomic), but that runs the risk of injuries caused by prematurity and underdeveloped lung function.  If the pregnancy is allowed to run its course, or if induction is attempted, the doctor should be prepared to deal with a shoulder dystocia situation, and should be prepared to deliver by cesarean section in the event of an emergency.

Risks of Macrosomia

Macrosomic babies are at risk for the following medical complications and injuries:

Mothers of macrosomic babies have a greater than normal risk of postpartum hemorrhage, and complications resulting from cesarean section.

Contact Us

If your baby weighed over 8 lbs., 13 oz. at birth and had medical problems, including birth trauma or shoulder dystocia, contact our medical malpractice lawyers at (855) 712-7818 or online for a no-charge consultation.  We will be able to examine your pregnancy records and determine whether the doctor failed to properly and timely diagnose macrosomia, and whether that failure caused your baby’s injuries.

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