What to Know About Measuring Fundal Height

Choosing to have a baby can be a magical experience. But there are also many unknowns that come with pregnancy. You’re doing everything you can to care for your body and your unborn child, but you may wonder how to know if your baby is growing well in your uterus (womb).

Measuring fundal height is one way to keep track of your baby’s development while you’re pregnant.

What Is Fundal Height?

It’s the distance from your pubic bone to the top of your uterus.

Measuring your fundal height is one test your doctor may do at your pregnancy check-ups. Other ways they may check on your baby’s health include checking your physical health, running labs on your body, listening to your baby’s heartbeat, checking how often your baby moves, and looking at your baby with an ultrasound.

Doctors combine all of these factors to give you the most accurate understanding of how well your baby is developing.

What Does Fundal Height Tell You About Your Baby?

Doctors use your fundal height measurement to test how well your baby is growing.

It’s one of many tests doctors use to measure your baby’s growth. Your fundal height is compared to your estimated pregnancy date to suggest whether your baby is growing on track.

If your fundal height isn’t what you expect it to be, it doesn’t automatically mean that there’s something wrong with your baby. But if your fundal height is on track, you may be able to rest a little easier knowing your baby is growing the way your doctors are expecting it to.

How Do You Measure Fundal Height?

Understand that even trained doctors can have a hard time measuring it accurately. So, before you try measuring fundal height at home, have your doctor show you where your pubic bone is and how to locate the top of your uterus.

Once you know, here are the basic steps to follow.

  1. Empty your bladder first. Studies show that a full bladder can change fundal height measurements by several centimeters.
  2. Next, lay down on your back with your legs out in front of you. Using a tape measure that measures centimeters, place the zero marker at the top of the uterus. 
  3. Move the tape measure vertically down your stomach and place the other end at the top of your pubic bone. This is your fundal height measurement.

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What Should Your Fundal Height Be?

Starting at 24 weeks, your fundal height should be about the same number of centimeters as the number of weeks you’ve been pregnant.

Your fundal height may be off by up to 2 centimeters in either direction and still be considered normal.

So, for example, if you’re 30 weeks pregnant, a fundal height of 28 to 32 centimeters is considered to be a normal range.

What Can Impact Fundal Height?

There are a number of things that can affect it. Not all of these factors have to do with your baby. For example, your fundal height measurement may not be accurate if:

There are other reasons your fundal height may be bigger or smaller than expected. If your fundal height is larger than expected, it may be because:

  • You have too much amniotic fluid.
  • You’re having more than one baby.
  • Your baby is larger than expected.

If your fundal height is smaller than expected, it may be because:

  • Your baby is smaller than expected.
  • You don’t have enough amniotic fluid.
  • Your baby’s growth is being restricted.

Your fundal height measurement may also be off if your pregnancy is further along, or less far along, than you thought. Your due date is an estimate based on the last day of your last period, so it can sometimes be inaccurate.

Doctors usually use the assumption that you have a standard 28-day period when making their due date predictions. Since periods and ovulation windows can vary, your doctor may have been off by a couple of weeks when first predicting your due date.

What Should You Do if You’re Concerned About Your Fundal Height?

If your fundal height isn’t measuring as expected, your doctor will need to do some follow-up tests to determine the root cause. These tests could include an ultrasound to get a better look at your baby or labs to test the health of your body.

An unusual fundal height measurement on its own is an indication that there’s something happening with your baby.

Once your doctor has figured out why your fundal height measurement is off, they can help you figure out what steps need to be taken next, if any, to help your baby grow at a healthy rate.

WebMD Medical Reference

Sources

SOURCES:

King Edward Memorial Hospital Obstetrics and Gynaecology: “Fundal height: Measuring with a tape measure.”

Mayo Clinic: “What’s the significance of a fundal height measurement?”, “Prenatal care: 2nd trimester visits.”

Ohio State University Wexner Medical Center: “What can cause your due date to be wrong?”

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