A medical term that describes a newborn who is larger than average is called fetal macrosomia. Babies who were diagnosed with this condition weigh more than 8 pounds, 13 ounces (4,000 grams), and no matter his/her gestational age. Approximately 9% of newborns weigh more than 8 pounds, 13 ounces in the entire world.
Fetal macrosomia risks elevate significantly if a newborn weight is more than 9 pounds, 15 ounces (4,500 grams). This condition also may cause vaginal delivery problems and put the newborn at risk of injury during birth. Moreover, a higher risk of different health conditions also is present in babies after birth.
Symptoms
Sometimes, it is challenging to identify this condition during pregnancy. Check below some symptoms:
- Polyhydramnios – It is also called excessive amniotic fluid and when it occurs the fluid that surrounds and protects the baby becomes too much. As a result, this is one symptom of the larger baby size. In addition, the amount of amniotic fluid shows the amount of urine the baby produces. However, there are some conditions that cause increased urine production in unborn babies.
- Large fundal height – The fundal height (the distance between the top of the uterus and the pubic bone) can be measured during pregnancy. If it is larger than should be it is also a symptom of fetal macrosomia.
While mild polyhydramnios cases do not require treatment, if a severe one occurs, you should consult with your doctor for treatment.
Causes
There are some genetic factors and maternal conditions (such as obesity or diabetes) that may cause fetal macrosomia. In rare cases, unborn babies may have certain health conditions that make them grow larger and faster. However, in some cases, it is not possible to determine the exact cause of this condition.
Risk Factors
There are multiple factors that elevate the risk of fetal macrosomia. Examples include:
- Maternal diabetes – This factor increases significantly the risk of fetal macrosomia and does not matter if you have had diabetes before or developed it during pregnancy. If you are not treating diabetes, it may lead to larger shoulders and an increased amount of body fat in the newborn.
- History of fetal macrosomia – If you have given birth to a large baby previously, there is an increased risk of fetal macrosomia on the next one.
- Maternal obesity – The risk of fetal macrosomia also increases if the biological mother is obese.
- Excessive weight gain during pregnancy – Elevated risk of this condition happens if you are gaining too much weight.
- Previous pregnancies – The risk of this condition increases with each pregnancy. For instance, on the fifth pregnancy, the average birth weight increases usually by about 3 ounces (113 grams).
- Boys – Generally, male infants are little more than female infants. Approximately all newborns who weigh more than 9 pounds, 15 ounces (4,500 grams) are males.
- Overdue pregnancy – A higher risk of fetal macrosomia occurs if the pregnancy continues by more than 14 days past your due date.
- Maternal age – If you are giving birth and you are over 35 years old, fetal macrosomia risk elevates.
Commonly, this condition happens due to maternal diabetes, obesity, or excessive weight gain during pregnancy. Sometimes, previous risk factors are not present, and fetal macrosomia is suspected. In such cases, there may be a rare condition that causes the baby to grow faster and larger.
Complications
This condition increases the risks for you and your baby either before or after birth. Check below some complications:
Maternal Risks
- Labor problems – This condition may cause a baby to become wedged in the birth canal (also called shoulder dystocia) and experience birth injuries.
- Genital tract lacerations – When fetal macrosomia occurs, the baby may cause injuries to the birth canal (including tearing vaginal tissues and muscles between the vagina and anus also called pineal muscles).
- Bleeding after delivery – This condition elevates the risk of uterine atony (a condition in which uterine muscles do not contract properly after birth). As a result, severe bleeding after birth may occur.
- Uterine rupture – Fetal macrosomia also increases the risk of a rare complication that causes the uterus to rupture during labor. Thus, an emergency C-section is required to prevent life-threatening complications.
Newborn and Childhood Risks
Check below some complications of fetal macrosomia for babies:
- High blood sugar levels – Babies with fetal macrosomia are more likely to be born with increased sugar levels in the blood.
- Childhood obesity – As per studies, childhood obesity risk is higher in children with fetal macrosomia.
- Metabolic syndrome – Children diagnosed with this condition are at increased risk of developing metabolic syndrome in childhood. A group of symptoms and conditions that happen at the same time is called metabolic syndrome. These include high blood pressure (hypertension), high sugar levels in the blood, excess body fat, especially around the waist, and high cholesterol. The previous symptoms put your child at higher risk of developing heart disease, diabetes, stroke, and other serious health problems.
How to Prevent Fetal Macrosomia?
While it is not possible to prevent fetal macrosomia, you can promote a healthy pregnancy. As per studies, adopting a low-glycemic diet during pregnancy may help reduce the risk of this condition. Examples include:
- Discuss with your healthcare professional if you plan to become pregnant and are obese.
- Regularly monitor your weight because it will help avoid excess weight during pregnancy. A healthy weight gain ranges between 25 to 35 pounds (approximately 11 to 16 kg).
- It is also advised to control blood sugar levels because it helps prevent complications (including fetal macrosomia).
- Follow your doctor’s recommendations for physical activity.
Diagnosis
However, it is not possible to diagnose this condition during pregnancy. After the baby is born and weighed, doctors may confirm the condition. Healthcare providers may perform some tests if you have risk factors for this condition. For example:
- Ultrasound – This test uses sound waves to make detailed images of different body structures and organs. In such cases, it is used to measure certain body baby parts (for example the head, abdomen, and femur).
- Antenatal testing – Doctors usually perform this test when they suspect fetal macrosomia, which includes a nonstress testing with ultrasound to monitor the baby’s tone, movement, breathing, and volume of amniotic fluid.
It is recommended to visit a pediatrician who has practice in treating babies with fetal macrosomia.
Treatment
Not every time a vaginal delivery is excluded when it is time for the baby to be born. However, talk with your healthcare professional about risks and benefits. During delivery, your doctor may monitor closely for potential symptoms of complications.
Sometimes, your doctor may recommend inducing labor by stimulating uterine contractions before it starts on its own. However, it is not recommended because some research showed that labor induction does not reduce risks associated with fetal macrosomia complications and may increase the need for a C-section. Doctors usually recommend this procedure in the following cases. For example:
- If you have diabetes before or develop it during pregnancy (also called gestational diabetes) and the weight of your baby is about 9 pounds, 15 ounces (4,500 grams) or more. In such cases, a C-section is one of the fastest ways to deliver the baby.
- C-sections also are required if the baby weighs 11 pounds (5000 grams) or more even if you do not have diabetes or gestational diabetes.
- Shoulder dystocia – Commonly, a C-section is performed when shoulder dystocia occurs. This is a complication of fetal macrosomia in which the baby gets stuck behind the pelvic bone.
After delivery, doctors usually perform different tests to check for high sugar levels in the blood, blood disorders (such as polycythemia), obesity, insulin resistance, and others. In any case, you should discuss with a healthcare professional if you want to become pregnant, especially if you have risk factors for fetal macrosomia.
Frequently Asked Questions
What are the most common causes of fetal macrosomia?
This condition often happens due to genetic mutations (changes) and maternal diabetes or obesity. The gender of the baby also contributes to this condition. For more details, talk with your doctor.
What health conditions are associated with fetal macrosomia?
There are some genetic disorders that are linked with a high risk of fetal macrosomia. These include Sotos syndrome, fragile X syndrome, Weaver syndrome, and Beckwith-Weidemann syndrome.
What are the most common complications of fetal macrosomia?
These include neonatal hypoglycemia, respiratory problems, and maternal or fetal trauma during birth. However, there are many other complications with an increased risk. If you have additional questions, ask your healthcare professional.
