Fetal Macrosomia

Fetal macrosomia is when your baby weighs more than the average baby regardless of their gestational age. Usually this is a birth weight that is over 8lbs 13 oz. Fetal macrosomia can be hard to predict or even prevent. It can however lead to complications during childbirth for both the mother and the baby.

Signs

If you are getting regular prenatal check ups your doctor will be looking for the signs of fetal macrosomia. There aren’t certain pregnancy symptoms that guarantee you will have a large baby. One of the signs is your fundal height. This is the measurement of your belly from the top of the uterus to the pubic bone. This measurement usually tracks at the same size as what gestational week you are. If you are 30 weeks your fundal height should be around 30 centimeters. A difference in this measurement can indicate that the baby is larger in size, smaller in size, or in a breech position. Another sign that your doctor will look for with fetal macrosomia is excessive amounts of amniotic fluid. The amount of amniotic fluid that there is reflects the baby’s urine output.

Causes & Risks

The exact cause of fetal macrosomia can sometimes be unknown. Genetics can play a part, if you and your spouse are bigger people, you may have bigger babies. The mother being obese can also play a role. Having a condition such as gestational diabetes can also cause fetal macrosomia. If you have birthed a child that has weighed more than 8 lbs 13 oz you have a higher risk of having another baby equally as large. If you have had more than one pregnancy it is normal for birth weight for each pregnancy to go up about 4 oz. Excessive pregnancy weight gain can also raise your risk of fetal macrosomia. Having a boy can also raise your risk. Being overdo. You have a higher risk of developing fetal macrosomia if your pregnancy goes beyond 40 weeks. Women who are over the age of 35 also have an increased risk. The three most common causes of fetal macrosomia are obesity of the mother, gestational diabetes, or excessive weight gain.

Complications

Fetal macrosomia can cause complications during childbirth. It raises the risk of vaginal tears. It can also cause injury to the birth canal. Raises the risk of postpartum hemorrhaging. Can also cause a uterine rupture. Long labors can also be a complication of fetal macrosomia, which can lead to changes in the baby’s heart rate during delivery. The most common complication for babies is shoulder dystocia. This is when the head emerges but the shoulders get stuck. This can lead to bone fractures, brachial plexus injury, or brain damage in the baby. Other complications for the baby include high red blood cell count which can raise the risk of jaundice, low blood sugar, or breathing problems.

Diagnosis

It can be hard to predict if your baby will be large. There is only so much measuring and tests your doctor can do to estimate your baby’s birth weight. At your prenatal appointments your doctor will check your fundal height usually starting around 20 to 24 week appointments. If your fundal height is measured ahead your doctor may also feel your belly. Sometimes by feeling your belly the doctor can get a better sense of how big the baby will be. If these two things indicate it is necessary your doctor may send you for a growth ultrasound. This is an ultrasound with the purpose of measuring your baby’s size and the amount of amniotic fluid. An ultrasound can only predict your baby’s weight within 10%. Meaning if the ultrasound predicts your baby to weigh 9 pounds, they could weigh anywhere between 8 and 10 pounds.

After the ultrasound your doctor will be able to help you decide how and when is the best time for you to have your baby. This could be inducing early, or scheduling a C section. Just because your baby is measuring large, you do not always have to have a C section to deliver your baby. Your doctor may recommend a C section if you have had a previous baby that had shoulder dystocia, you have gestational diabetes and your baby is estimated to measure above 10 pounds, or you do not have diabetes and your baby is estimated to measure above 11 pounds.

Tips For Handling Fetal Macrosomia

With fetal macrosomia the first rule of treatment is to control underlying conditions. If you are obese or suffer from gestational diabetes, getting these conditions under control can help the size of your baby. This could be as easy as making some diet modifications, and making sure you get enough daily exercise. In some cases with gestational diabetes insulin is needed to control the condition. Working with your doctor to manage this can be helpful in your health as well as your baby’s. Managing your pregnancy weight gain can also be essential in helping your baby not be too large. If you have a normal healthy weight before becoming pregnant, normal weight gain during pregnancy is between 25 and 35 pounds. It is also important for you to get exercise during your pregnancy.