5 Signs You're Having a Big Baby

Wondering if you're having a big baby? Here are some signs you might have a bigger bouncing bundle of joy on your hands.

Pregnant Women Holding Ultrasound Image
Photo: Natalia Deriabina/Shutterstock

If you're pregnant and have ever wondered how big your baby will be at delivery, you're not alone. Many expecting parents wonder how much their little one will weigh when they are born.

Not only is it just plain fun to try to guess your baby's size, but there are practical reasons you might want to know how big your baby is. For instance, should you stock up on newborn diapers or will you need preemie sizes? Should you skip the newborn onesies and head right to 0-3 months? What about even bigger sizes?

There isn't always an exact science to predicting how big your baby might be, but here are a few facts about "big" babies and some ways you (and your doctor) may try to tell if you're having a big baby.

What is a "Big" Baby?

Medically speaking, a big baby is known as fetal macrosomia and refers to any baby that is born weighing more than 8 pounds and 13 ounces. In the U.S., the average baby weighs just over 7.15 pounds. UpToDate also notes that in some wealthier countries, the threshold of 9 pounds, 15 ounces may be used.

The true rate of fetal macrosomia is relatively small, at around 9% of babies worldwide. But there are some risks to a baby having fetal macrosomia to both the person delivering the baby and the baby as well. And the bigger your baby is, the more the risks can increase.

Potential Risks of Having a Big Baby

For the person going through delivery, some of the risks that a larger baby might bring include:

  • Increased risk of bleeding with labor and delivery
  • Injuries to your body from delivery
  • Longer labor
  • Increased need for C-section
  • Increased need for labor interventions, such as a vacuum

Your baby may also be at a risk for some health complications if they are diagnosed with fetal macrosomia. For instance, larger babies often have:

  • Trouble regulating their sugar
  • Jaundice
  • Breathing problems
  • Increased risk of injury during birth

There is also some evidence that large babies may go on to develop insulin resistance later in life, which can cause additional medical complications such as diabetes and obesity.

5 Signs You're Having a Big Baby

Doctors use a few different methods to help predict how big your baby might be, although no one method will be 100% accurate.

Here are a few clues your doctors may use to help determine if your bouncing bundle of joy will be on the bigger side.

1. Your pregnancy stomach measures larger than average

One way to help determine an estimate of fetal size will be based on how big your belly measures. If your stomach measures large for dates—meaning that your pregnant stomach measures larger than most people at that week of pregnancy—the doctors may assume it's because you are housing a larger baby inside.

However, there are other reasons you might have a larger-than-average baby too, so again, that's not always an exact method. You may have extra skin or tissue on your abdomen or you may have extra amniotic fluid, both of which can increase your measurements too.

2. You have extra amniotic fluid

Speaking of excess amniotic fluid, if your doctor lets you know that your amniotic fluid levels are higher-than-normal, this could also be a sign that you might be having a big baby. The Mayo Clinic explains that extra amniotic fluid (a condition called polyhydramnios) is often associated with larger-than-average babies.

Amniotic fluid is produced by babies' urine (yes, really!), so the larger the baby, the more amniotic fluid they can make.

However, again, there can be different reasons for extra amniotic fluid and this is not always a guarantee you'll have a large baby, but it could be a sign your doctor may monitor.

3. Your ultrasound predicts a large baby

Ultrasounds are better indicators of fetal size, but even the more advanced 3D ultrasounds aren't always accurate in predicting how big your baby will be. In fact, according to a 2018 study review, ultrasounds actually tend to overestimate how big babies are. So even if your doctor determines that you've got a big baby on board, their actual weight at delivery may be far less.

4. You have had a large baby before

In general, pregnant people tend to deliver heavier babies with each pregnancy and while it's not a hard-and-fast rule, if you have had one ore more large babies in the past, you are up to 10 times more likely to have a big baby again in the future.

5. You have gestational diabetes

Pregnant people with gestational diabetes tend to have larger-than-average babies, especially if the diabetes is not controlled well with diet or insulin. On average, people with gestational diabetes have a 2-3 higher rate of babies with fetal macrosomia than people without gestational diabetes.

So You Have a Big Baby, Now What?

While it might seem overwhelming to hear the potential risks associated with a big baby, it's important to keep in mind that just because you're having a larger-than-average baby, that doesn't necessarily mean that something will go wrong. (And I'm speaking from experience here, as the mom of huge babies and someone who had polyhydramnios too!) Sometimes, babies are just bigger and that doesn't always mean anything is wrong.

Your doctors will do an excellent job in monitoring you and your baby's health and if any complications are suspected, they will offer you a plan to minimize any potential risks. And on your end, all you can do is continue to eat a well-balanced diet, exercise as appropriate, and manage any health conditions you may have during your pregnancy.

After your baby is born, if their size is determined to be larger than average, they will most likely get their blood sugar tested to ensure they are able to stabilize their blood sugars. But if all checks out, it's back to your arms for some big baby snuggles.

Was this page helpful?
Related Articles