Pregnant with a Large Baby (Macrosomia): Causes, Risks and Prevention


Macrosomia is used to describe a baby who is significantly born larger than average.  A baby diagnosed with this condition has a birth weight of more than 8 pounds, 13 ounces (4000 grams), regardless of the gestational age. In addition to a difficult delivery, macrosomia can also increase the risk for a cesarean delivery(C-section) and injury to the baby during birth. In this article, we will look at some of the risk factors, causes and all about macrosomia.

All You Need to Know About Macrosomia


Causes of Macrosomia

A number of causes of this condition include:

  • Diabetes in the mother
  • Genetics
  • Medical condition in the baby
  • Obesity in the mother

There are higher chances of having a baby with macrosomia if:

Symptoms of Macrosomia

Birth weight of more than 8 pounds, 13 ounces is the main symptom of macrosomia, which is regardless of the fact if the baby was born early, on time or late.

Can it be diagnosed?

There are a number of methods to check the baby’s size. Your healthcare provider would also want to know about your medical history. Some of the methods to check the baby’s size include:



Sound waves are used in order to create an image of the baby in the uterus. however, the test may not be completely accurate but it can give an estimation of whether the baby is too large in the womb or not.

Nonstress test

Nonstress test is conducted in order to measure your baby’s heartbeat whenever he/she moves.

Check the amniotic fluid level

Larger babies produce comparatively more urine. Excessive amniotic fluid is a sign that the baby is producing excess urine.

Biophysical profile

This test is a combination of the nonstress test and the ultrasound to assess the baby’s breathing, movements and level of amniotic fluid.

Measuring the height of fundus

The length from the top of mother’s uterus to the pubic bone is what is called as, fundus. In case the fundal height is larger than the normal height, it is a sign of macrosomia.

Does It Affect Delivery?

Macrosomia can lead to some problems during delivery. You may also need to schedule a cesarean delivery in case your healthcare provider thinks that your baby’s size could cause complications during a vaginal delivery.


Some of the problems are listed below:

  • The labor may take longer than usual
  • Cesarean delivery is needed
  • The baby lacks sufficient oxygen
  • The baby’s clavicle or another bone gets fractured
  • The baby’s shoulder can get stuck in the birth canal
  • Vacuum delivery is needed

Can it lead to any complications for the mother and baby?

Yes. Macrosomia can be problematic for both the mother as well as the baby. listed below are a few problems that may arise with the mother:

Bleeding after delivery

A large size baby can prevent the contraction of the uterus muscles the way they should after delivery. This can lead to excess bleeding after delivery.

Uterine rupture

The uterus can tear during delivery if you have had a past caesarean delivery or uterine surgery in the past. This condition can also be life threatening.

Injury to the vagina

The baby can tear the mother’s vagina and the perineal muscles (the muscles between the vagina and anus), as he/she is delivered.

Problems that may arise with the baby


Abnormal blood sugar

There are some babies who are born with lower than normal blood sugar.


Babies are more likely to be obese in childhood if they are born at a heavier body weight.

In addition to this, large size babies are also at a risk for the following conditions in adulthood:

  • Diabetes
  • Obesity
  • High blood pressure

Metabolic syndrome is another risk that the baby may develop. High blood pressure, excess fat around the waist, high blood pressure and abnormal cholesterol levels are certain conditions. On growing older, the metabolic syndrome can lead to an increased risk of conditions like heart disease and diabetes.



Although fetal macrosomia cannot be prevented but one can promote a healthy pregnancy by following a few measures. It is important that you schedule a preconception appointment with your doctor if you are considering pregnancy in the future. In case you had diabetes or develop the same during pregnancy, consult your healthcare provider in order to work through this condition. One can also try to include physical activity in their daily routine by following their healthcare provider’s recommendations.


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