Natural Childbirth, Large Baby: Worried? Read This.

Natural Childbirth Large Baby. Worried? Read This.

Updated on May 30th, 2021 // by Katie Griffin

The last few weeks of your pregnancy are finally here!  But your doctor is telling you that you might have a large baby and you’re starting to worry.  “Will I have to have an induction or possibly a c-section?  Does this mean I have to abandon my plans for a natural childbirth?” Mama, take a deep breath and READ ON! It is possible to have a natural childbirth with a large baby!

Estimated reading time: 5 minutes

Natural Childbirth Large Baby:  Fetal Macrosomia

The average birth weight for babies in the United States is 7lbs, 5oz.  “Fetal macrosomia” is the term that describes a newborn who is larger than average, weighing over 8lbs 13 oz. (1).

In low-risk pregnancies, only 3.6-6% of babies will be born large.  However, it is much more common when mom has gestational diabetes, because baby is exposed to sustained high glucose levels. This risk is decreased by treating the diabetes according to your doctor’s recommendations.

Don’t worry — Most babies born to healthy moms will NOT be significantly larger than average weight.

Natural Childbirth Large Baby Fetal Macrosomia

What Are the Risks?

When born vaginally, large babies are at an increased risk for birth trauma, such as shoulder dystocia.  Shoulder dystocia is a complication in which the head is delivered through the vagina but the shoulders are too wide and get stuck inside mom’s body.  Fortunately, it’s rare, occurring in only 1.4% of vaginal births.

With that said, when baby weighs over 8lbs 13oz, the risk for shoulder dystocia does increase.  If mom has untreated gestational diabetes, the risk jumps to 19.9-50% (2).

Don’t worry — For the vast majority of births, complications like shoulder dystocia are rare.

Natural Childbirth Large BAby What Are the Risks

How is it Diagnosed?

According to ACOG, weighing the baby after delivery is the ONLY way to accurately diagnose macrosomia (3).

However, macrosomia is often “diagnosed” during pregnancy, possibly innacurately:

  1. In the doctor’s office by measuring the uterus with a measuring tape (measuring the height of the fundus above the symphysis pubis)
  2. Ultrasound measurements taken late in the pregnancy

Don’t worry — No healthcare provider can know the exact size of your baby prenatally, even if they do an ultrasound.  

Natural Childbirth Large Baby How is it Diagnosed

Prenatal Measurements are Inaccurate

Research reveals that these prenatal measurements of baby’s weight are usually inaccurate (3).  To illustrate this, a recent survey found that 32% of women were told during pregnancy that their baby might be getting too large.  Of these women, the actual average birth weight of their babies ended up being only 7lbs 13oz (4).  This is well below the size limits of macrosomia.  For a healthy woman with a low-risk pregnancy, there is a strong likelihood that your baby is an average size, despite any prenatal measurements.

Don’t worry — Many moms are told prenatally that their baby might be too large.  These predictions are usually wrong.

Natural Childbirth Large Baby Prenatal Measurements are Inaccurate

Natural Birth, Large Baby: The Take-Home Message:

  1. Take good care of yourself during pregnancy.  Eat healthy foods and exercise regularly.  Despite your best efforts, some moms will develop gestational diabetes.  In this case, proactively treat the medical condition according to your doctor or midwife’s recommendations to help prevent fetal macrosomia.
  2. Don’t pay too much attention to prenatal measurements of your baby’s size.  There’s no way you can know your baby’s size for sure until he or she is born and on the scale.  Remember that measurements taken in prenatal ultrasounds are often inaccurate.
  3. Continue to plan and prepare for a natural childbirth.  Chances are, baby will be born without a hitch.  When the big day comes, work with your body and your healthcare provider to make choices that will bring about the best and safest birth for you and your baby.

Kopa Birth’s online childbirth classes allow you to prepare for a natural childbirth from the comfort of your own home, 24/7. Enroll today in our free online childbirth class to learn more about preparing for a natural hospital birth.


  1. Olds, S. B., London, M. L., & Ladewig, P. W. (2000). Maternal-newborn nursing: A family and community-based approach. Upper Saddle River, N.J: Prentice Hall Health, 359.
  2. Usta, A., Usta, C. S., Yildiz, A., Ozcaglayan, R., Dalkiran, E. S., Savkli, A., & Taskiran, M. (2017). Frequency of fetal macrosomia and the associated risk factors in pregnancies without gestational diabetes mellitus. The Pan African Medical Journal26, 62.
  3. American College of Obstetricians and Gynecologists. Fetal macrosomia. Practice Bulletin No. 173.  Obstet Gynecol 2016;128:e195–209.
  4. Declercq, E.R., Sakala, C., Corry, M.P., Applebaum, S., Herrlich, A. (2013). Listening to Mothers III: Pregnancy and Birth. New York: Childbirth Connection.

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Meet Katie Griffin

I’m a registered nurse, Lamaze certified childbirth educator, and the mother of 7. I help women realize their dream of a natural, intimate, and empowering hospital birth.

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