Some newborns who are born much larger than typical for their gestational age—the number of weeks they spent in the womb—are affected by a disorder called macrosomia. Regardless of when they were delivered, a newborn with macrosomia weighs more than eight pounds, thirteen ounces (4,000 grams). Globally, 9% of newborns are born with macrosomia.
During and after delivery, macrosomia can lead to complications for both the mother and the child. Additionally, it may raise the chance of developing health issues like diabetes and obesity later in life. For this reason, understanding macrosomia's origins, symptoms, diagnosis, course of therapy, and prevention is crucial.
There are many factors that can contribute to macrosomia, some of which can be controlled and some of which cannot. The most common causes are:
Maternal diabetes. If the mother has diabetes before or during pregnancy, her blood sugar levels may be too high. This can make the baby grow faster and larger than normal, especially in the upper body. The baby may also have more body fat than usual.
Maternal obesity. If the mother is obese before or during pregnancy, she may have higher levels of insulin and other hormones that can stimulate the baby’s growth. She may also have more difficulty controlling her blood sugar levels, which can affect the baby’s size.
Genetics. Some babies are naturally larger than others due to their genes. If the parents or siblings were large at birth, the baby may inherit this trait. The baby’s sex may also play a role, as boys tend to be heavier than girls.
Medical condition in the baby. Rarely, a baby may have a medical condition that causes him or her to grow faster and larger than normal. For example, some genetic disorders, such as Beckwith-Wiedemann syndrome, can affect the baby’s growth and development. Some hormonal imbalances, such as congenital adrenal hyperplasia, can also cause macrosomia.
Macrosomia is characterized by a birth weight more than eight pounds, thirteen ounces. Since it is impossible to pinpoint the baby's exact weight before birth, diagnosing this condition can be challenging. Doctors may thus search for other indicators and symptoms, such as the following, that point to a larger-than-average baby:
Large fundal height. The fundal height is the distance from the top of the uterus to the pubic bone. It is measured during prenatal visits to check the baby’s growth. A larger than expected fundal height could be a sign of macrosomia.
Excessive amniotic fluid. The amniotic fluid is the liquid that surrounds and protects the baby in the womb. The amount of amniotic fluid reflects the baby’s urine output, and a larger baby produces more urine. Having too much amniotic fluid, also known as polyhydramnios, could be a sign of macrosomia.
Large body parts. An ultrasound scan can be used to measure the baby’s body parts, such as the head, abdomen, and limbs. If the measurements are larger than normal for the gestational age, it could indicate macrosomia.
Macrosomia is diagnosed when the baby is born and weighed. However, doctors may suspect macrosomia before delivery based on the signs and symptoms mentioned above. They may also use some tests to estimate the baby’s weight and check for any complications, such as:
Ultrasound scan. This test uses sound waves to create an image of the baby in the womb. It can measure the baby’s body parts and estimate the weight. However, this method is not very accurate and may overestimate or underestimate the actual weight by up to 15%.
Nonstress test. This test measures the baby’s heartbeat as he or she moves. It can show how the baby responds to stimuli and if there is enough oxygen supply. A healthy baby should have a regular and strong heartbeat that increases with movement.
Biophysical profile. This test combines the nonstress test with an ultrasound scan. It assesses the baby’s breathing, movements, muscle tone, and amniotic fluid level. A score of 8 or 10 out of 10 indicates a normal and healthy baby.
The treatment of macrosomia depends on the severity of the condition, the gestational age, and the health of the mother and the baby. The main goal is to deliver the baby safely and prevent any complications. The possible treatment options are:
delivery by vagina. Vaginal birth is a possibility if the baby is not too big and there are no additional risk concerns. In order to help the infant travel through the delivery canal, further assistance—such as the use of forceps or a vacuum—might be necessary. In order to avoid tearing, the mother could additionally require an episiotomy, or perineum incision. In addition, the infant could require cautious observation for any indications of harm or discomfort both during and after delivery.
A cesarean delivery may be required if the baby is too big or if there are other issues, including shoulder dystocia, when the baby's shoulder becomes lodged in the birth canal. This is a medical process where the baby is delivered by creating an incision in the uterus and abdomen. While there is a chance of infection, bleeding, and a lengthier recovery period, this can help protect both the mother and the unborn child from harm.
It's critical to treat the mother's diabetes and obesity both before and throughout pregnancy. By doing this, the likelihood of macrosomia and its consequences may be decreased. The mother has to take her medications as directed by her physician, maintain a nutritious diet, exercise frequently, and keep an eye on her blood sugar levels.
Some cases of macrosomia cannot be prevented, such as those caused by genetics or medical conditions in the baby. However, some cases can be prevented or reduced by addressing the modifiable risk factors, such as:
Before becoming pregnant, the woman should speak with her doctor if she has a history of macrosomia or any other illnesses that may have an impact on the baby's growth, such as diabetes or obesity. The physician can provide her with advice on how to lower her risk of difficulties and be ready for a safe pregnancy.
Along with adhering to the doctor's advice, the mother should attend all of her prenatal appointments on time. The physician can keep an eye on the infant's growth and development, check for issues, and perform any required procedures. Additionally, the mother should contact her doctor as quickly as possible with any symptoms or concerns.
Pregnancy should begin and end with the woman maintaining a healthy weight. The baby's growth may be impacted by her gaining too much or too little weight, so she should avoid doing either. The mother's body mass index (BMI) and other variables might be used by the doctor to determine how much weight to gain.
Before and during her pregnancy, the woman should maintain blood sugar levels within the usual range. By doing this, diabetes and its repercussions on the developing infant can be avoided or managed. The mother has to follow her doctor's prescriptions for any medications, maintain a balanced diet, and stay away from items that cause blood sugar spikes.
