OVERVIEW

What is macrosomia?

Macrosomia refers to a newborn with a birth weight equal to or greater than 4,000 grams (more than eight pounds).

What risks might macrosomia pose to the mother?

Macrosomia may pose the following risks to the mother:

• Prolonged or arrested labor;
• Operative vaginal delivery;
• Increased cesarean section rate;
• Genital tract lacerations and postpartum hemorrhage;
• Uterine rupture, etc.

What risks might macrosomia face during birth?

Macrosomia may encounter the following risks during delivery:

• Birth injuries due to shoulder dystocia, such as brachial plexus injury, fractures, etc.;
• Neonatal asphyxia;
• Neonatal hypoglycemia, etc.

What risks might macrosomia face later in life?

As macrosomic infants grow older, they are at higher risk of developing conditions such as:

• Impaired glucose tolerance and obesity;
• Metabolic syndrome;
• Increased aortic intima-media thickness;
• Left ventricular hypertrophy;
• Dyslipidemia, etc.

Is macrosomia common?

Yes. Approximately 9%–10% of newborns are macrosomic. With continuous improvements in living conditions, the incidence of macrosomia is further increasing.

SYMPTOMS

What are the manifestations of macrosomia?

• The most obvious manifestation is the baby's large body weight and excessive subcutaneous fat.
• If complications occur, there may be manifestations such as refusal to feed, pale complexion, lack of crying or fussing, and asymmetrical hand movements.

CAUSES

What are the causes of macrosomia?

• Elevated blood sugar during pregnancy, such as gestational diabetes, is a common factor leading to excessive fetal weight.
• Unhealthy maternal diet during pregnancy, excessive nutrient supplementation, maternal obesity, or excessive weight gain during pregnancy may also result in a large fetus.
• Genetic factors: If parents are tall or large in stature, the child may also be large, increasing the likelihood of macrosomia.

DIAGNOSIS

How to detect macrosomia early?

Fetal ultrasound is the standard method for diagnosing macrosomia.

Ultrasound is used to estimate fetal abdominal circumference and weight, with abdominal circumference (AC) being the most commonly used and reliable single parameter for assessing the risk of macrosomia.

The most commonly used threshold for predicting macrosomia is an AC of 35–38 cm. The sensitivity of AC measurement depends on the chosen threshold, the definition of macrosomia, and the gestational age at the time of examination.

What tests should be performed after the birth of a macrosomic baby to screen for potential risks?

• Blood glucose monitoring: Since macrosomic babies are prone to hypoglycemia, blood glucose should be monitored, and feeding should be initiated early to maintain stable glucose levels.
• Physical examination: Assess for complications such as clavicle fractures, brachial plexus injuries, or cephalohematoma.
• Chest X-ray: Can detect clavicle fractures.
• Electromyography (EMG): Helps evaluate the severity of brachial plexus injuries.

What should be noted when conducting postnatal tests for macrosomic babies?

If a macrosomic baby shows symptoms after birth, hospitalization is required, and the resident physician will arrange the necessary tests.

Chest X-rays can usually be performed at the bedside. For EMG, the baby may need oral sedatives, which are safe under medical supervision. The sedatives typically lose their effect within half an hour, so there is no need to avoid the test due to fear of sedation.

TREATMENT

Which department should a macrosomic baby see?

Generally, macrosomic babies do not require deliberate medical visits. However, if any complications arise, they may need to visit departments such as neonatology, neonatal intensive care unit (NICU), or obstetrics.

How is macrosomia treated?

Macrosomic babies without symptoms or complications do not require hospitalization. After blood glucose monitoring, they can stay with their mothers in the same room for care.

If symptoms such as asymmetrical hand movements, inability to lift or grasp objects, palpable lumps on the collarbone or head, refusal to feed, or pale complexion are observed, pediatric assistance should be sought to assess for complications.

Severe complications may require admission to a neonatal ward or NICU for treatment.

Do all macrosomic babies require a cesarean section?

• If prenatal ultrasound suggests a large fetal weight, it does not necessarily mean a cesarean section is the only option. Ultrasound estimates may have deviations. The decision should also consider the mother’s pelvic and birth canal conditions. Foreign cohort studies show that vaginal delivery can still be attempted even if the estimated fetal weight exceeds 4,000 g.
• A cesarean section should be considered if the mother has gestational diabetes and the estimated fetal weight exceeds 4,500 g, or if the estimated fetal weight exceeds 5,000 g.
• If the estimated fetal weight exceeds 4,500 g and there is prolonged second-stage labor or delayed fetal head descent, a cesarean section should be considered.
• For excessively large fetal weight, inducing labor with medication is not recommended. Instead, natural labor onset should be awaited.

What should be noted during hospitalization if a macrosomic baby has other accompanying conditions?

In non-accompanied wards, mothers should maintain breast milk production. Regularly express milk and store it in breast milk storage bags for freezing. This ensures the baby has breast milk after discharge, which is highly beneficial for long-term health.

Moreover, the beneficial components in breast milk promote nerve cell growth, and the act of breastfeeding helps soothe the baby and strengthen the mother-child bond, aiding recovery.

In accompanied wards, mothers can continue direct breastfeeding while cooperating with medical treatment.

Do macrosomic babies require follow-up after discharge?

Regular infant health check-ups are sufficient after discharge. The first check-up is typically at 42 days postpartum to assess developmental progress.

DIET & LIFESTYLE

What should be noted in the diet of macrosomic infants after birth?

No special precautions are needed, and breastfeeding is still the preferred choice.

What should be noted in the daily life of macrosomic infants after birth?

Ensure adequate feeding, start breastfeeding as early as possible, and feed on demand.

Due to their larger size, macrosomic infants require more milk than other babies. If the baby becomes fussy or cries less than an hour after feeding, frequent feedings can ensure sufficient nutrition. Avoid hypoglycemia caused by insufficient feeding.

Should pregnant women lose weight before delivery if the fetus is macrosomic?

If prenatal examinations indicate excessive fetal weight, the mother should undergo diabetes screening.

If abnormal blood sugar levels are detected, dietary control should be implemented to maintain normal glucose levels. If dietary control is difficult, insulin may be used under medical supervision to regulate blood sugar, which can help reduce the likelihood of delivering a macrosomic baby.

However, if the mother has no blood sugar abnormalities but the fetus is overweight, timely dietary control measures should be taken to help lower the risk of macrosomia.

PREVENTION

Can macrosomia be prevented?

Regular prenatal check-ups during pregnancy can help reduce the occurrence of macrosomia. If high blood sugar in the mother or fetal weight exceeding the average for gestational age is detected, timely measures such as dietary control should be taken.

Due to the limitations of prenatal ultrasound, fetal weight may not always be predicted with complete accuracy. If macrosomia is identified shortly before delivery, following the doctor's advice on the safest delivery method for both mother and child can help minimize the risk of dystocia.