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Fetal Macrosomia

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The term Fetal Macrosomia refers to the newborn with excessive birth weight. Generally, the average newborn weighs between 2,500 g to 4000 g.  Infants with macrosomia are susceptible to other conditions like diabetes and obesity later in life.

Fetal Macrosomia refers to newborns with birth weight greater than 4000 g or 4500g or in the 90th percentile of gestational age. A baby with Fetal Macrosomia is at increased risk of health problems after birth. Macrosomia can cause difficulty in delivery, increase the risk for cesarean delivery, and cause injury to the baby during delivery.

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What are the Causes of Fetal Macrosomia?

Maternal conditions and genetic factors such as obesity or diabetes can lead to Fetal Macrosomia. Factors associated with Fetal Macrosomia include:

  • ● Genetics
  • ● Long gestation period
  • ● Maternal diabetes or newly developed gestational diabetes.
  • ● Increased weight gain during gestation and class A, B, and C diabetes mellitus.
  • ● Ethnic, genetic, racial, and sex factors influence birth weight and increase the risk of macrosomia.
  • ● A medical condition in the baby.
  • ● Pre-pregnancy (BMI) body mass index is high.
  • ● History of macrosomia in previous pregnancies.
  • ● Mother being a macrosomic baby.

What are the Complications of Fetal Macrosomia?

Mother and baby both develop complications from Fetal Macrosomia.

Complications to mothers include:

  • Vaginal injury: During delivery, the fetus may damage the birth canal, such as a vaginal tear or the perineal muscles (the muscles between the vagina and anus).
  • Bleeding after delivery: The uterus may not contract after delivery due to a large baby causing excessive bleeding.
  • Rupture of the Uterus: The uterus can damage during delivery in patients with past cesarean section or uterine surgery; this is a life-threatening complication.

Complications to babies include:

  • Obesity: Infants that are born heavy are likely to develop obesity in the early years.
  • Abnormal blood sugar: Some infants have low sugar levels. Rarely, blood sugar levels are high.

What are the Symptoms of Fetal Macrosomia?

Fetal Macrosomia includes the following symptoms:

  • Larger fundal height: The distance from the top point of the uterus to the public bone is fundal height. Fetal Macrosomia presents with a distance greater than usual and expected.
  • Polyhydramnios: The volume of the amniotic fluid (the fluid surrounding the fetus and protects it) increases more than usual due to the large fetus, which produces excessive urine contributing to the amniotic fluid volume.

How is Fetal Macrosomia Diagnosed?

It is difficult to detect and diagnose Fetal Macrosomia during pregnancy. However, the doctors measure the birth weight after the child delivery to confirm the diagnosis retrospectively. If they suspect the baby to be larger than usual, they conduct the following diagnostic methods:

  • ● Measure the height of the fundus.
  • ● Ultrasound, this test uses sound waves to view an image of the fetus in the uterus. However, the accuracy of ultrasound for predicting fetal macrosomia has been unreliable.
  • ● The nonstress test includes measuring the cardiac rhythm of the fetus in the womb.
  • ● Measure amniotic fluid level.
  • ● Biophysical profile, this test combines the nonstress test and ultrasound test to monitor the functioning, movement, breathing, and amniotic fluid level of the baby.

How is Fetal Macrosomia Treated?

It is challenging for the practitioners to treat fetal macrosomia because there could be shoulder dystocia to the fetus with permanent brachial plexus injury. In most complex cases, cesarean delivery is preferable to avoid complications and high labor pain during pregnancy.

What are the Interventions for Suspected Fetal Macrosomia?

Generally, the doctors suggest the following strategies to manage suspected Fetal Macrosomia:

  • Elective C-section delivery: Surgical procedure carried on conformed Fetal Macrosomia cases to avoid unfruitful labor and save from birth trauma.
  • Elective induction of labor: Elective labor induction is the best option before or near term to prevent macrosomia. Medications like prostaglandins, Pitocin are often used for early induction of labor.

Cesarean section is preferable for the following conditions:

  • Maternal diabetes: For women with diabetes and gestational diabetes, the safe delivery option is C-section.
  • Large babies: If the estimated baby weight is 5000 grams or more in a non-diabetic mother, the doctors consider a C-section.
  • Shoulder dystocia: Shoulder dystocia happens when the infant’s anterior shoulder gets stuck above the maternal pelvic symphysis (pelvic bone) during childbirth. Doctors recommend a C-section in mothers who had a delivery of a baby with shoulder dystocia previously.

What are the Results and Risks Associated with Fetal Macrosomia treatments?


Fetal Macrosomia – The baby’s excessive birth weight is difficult to predict accurately before childbirth (prenatally). However, modern diagnostic tools and tests promise better prediction of Fetal Macrosomia soon. Antidiabetic medications are advisable for diabetic pregnant mothers. In general, the specialists recommend daily physical activity, weight management as some preventive measures to the suspected patients.


Risk of Fetal macrosomia C-section delivery

  • Delivery problems: A macrosomic baby is large, it is difficult to pass through the birth canal; hence the preferable option is vacuum or C-section.
  • Rupture of the uterus: If the mother had a C-section in the first delivery, there is a risk of uterus tearing and opening from the scar along the C-section line from the previous c-section.
  • Lacerations of the genital tract: During delivery, the fetus may damage the birth canal, such as a vaginal tear or the perineal muscles (the muscles between the vagina and anus).
  • Bleeding: The uterus may lose its strength and not contract after delivery due to a large baby causing excessive bleeding.
  • Infection of the wound: After C-section, there is a risk of wound infection causing swelling, pain, redness, and wound discharge.
  • Infection of the uterine lining: After a C-section, there is a risk of infection of the uterine lining. Symptoms may include abdomen pain, fever, heavy vaginal bleeding, and abnormal vaginal discharge.
  • Deep vein thrombosis (DVT): There is a risk of a blood clot in the legs that can lead to swelling and pain and becomes very dangerous when travels to the lungs.
  • Damage to the bladder or ureter may require further surgery.

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What Causes Fetal Macrosomia?

Genetics, duration of gestation, gestational diabetes, high body mass index (BMI) during pregnancy are some of the causes of Fetal Macrosomia.

Mention Some Health Complications of Fetal Macrosomia?

Babies with Fetal Macrosomia tend to have low blood sugar levels; and may also have a high risk of obesity, jaundice, and metabolic symptoms in the later stages of life.

How is Fetal Macrosomia Diagnosed?

Fetal Macrosomia diagnosis is always after the delivery. The doctors recommend a physical examination, ultrasound, nonstress tests in the suspected pregnant mothers.

Mention Some Preventive Measures to Avoid Fetal Macrosomia?

Fetal Macrosomia might not be preventable, but we can promote a healthy pregnancy. Research shows that exercising during pregnancy and eating a low-glycemic diet can reduce the risk of Macrosomia.

What are the Early Signs of Fetal Macrosomia?

An early sign of Fetal Macrosomia includes a larger fundal height.

6. Mention some Complications to the Mother During the Vaginal Delivery of the Fetus?

Difficulty in delivering a baby, higher labor pain, tissue tear, bleeding after delivery are some complications commonly seen.

What Increases the Risk of Fetal Macrosomia?

Risk factors of Fetal Macrosomia include maternal obesity, diabetes, post-term pregnancy, and excessive weight gain due to pregnancy.


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