Fetal Macrosomia

laborWe read headlines of record-breaking birth weights and we wonder how on earth such enormous babies are born. However, even as delightful as it might be to see the round and jolly faces of large babies, such pregnancies and deliveries are serious matters. In fact, a baby who is large for their gestational age is said to be suffering from fetal macrosomia.

What Is Fetal Macrosomia?

We know that no two humans are alike, but we also know that there are “norms” for things like human development and growth. This applies to use even before we are born and most pregnancies have a range of different developmental stages. Babies at each stage tend to fall within those ranges, and so there are babies who might be a bit under the norm and those who are over the norm. In either instance, there will be the need for proper medical attention as it could mean the baby is at risk.

In the case of fetal macrosomia, the baby usually has a weight that puts them in a range higher than around 90% of the other babies in that same range. This is why the AAP or American Academy of Pediatrics says that only ten percent of pregnancies qualify as fetal macrosomia. Most medical experts put the average weights of full term babies between eight pounds and thirteen ounces to nine pounds and fifteen ounces. So, any baby more than that higher weight is going to be one who is at risk.

What Are the Risks?

Generally, one of the most common risks to an overly large baby is birth injury. After all, if they are so large as to be above the norm, it can mean they will be too large to get through the birth canal easily or safely. From delayed birth-to-birth asphyxia because they are stuck in the birth canal, the baby with fetal macrosomia is at great risk.

In fact, both the mother and baby are at risk for medical issues, and most often during delivery. A large baby may require a lot of assistance passing through the canal or may even force the need for an emergency cesarean section.

And while many wonder how an over-sized baby can end up being a surprise, the reality is that it can be very challenging to determine if a baby is indeed suffering from fetal macrosomia during most of the pregnancy. Some key indicators include excessive abdominal fluid and longer fundal height, but even these may not alert physicians to the true size of the baby.

Causes Are Cause for Concern

That means that the causes for fetal macrosomia may be something to consider. For example, a mother with diabetes is someone often at risk for a baby with the condition. A set of parents who are also viewed as being above the norm in terms of body size may be at risk, and interestingly enough mothers of Hispanic descent may be at a higher risk, too. Male children are more often oversized and mothers of advanced age (over 35) are also at risk.

If a mother does have such risk factors, it is a wise idea to consider exploring and/or monitoring fetal growth to gauge whether or not macrosomia is an issue. There are some steps that can be taken to reduce the risks to mother and child, including a planned cesarean section, controlled weight gain, and more. And while you cannot prevent fetal macrosomia, simple awareness of the risks is often enough to prevent the birth injuries so common to infants born with the condition.


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