Fundal Height

Fundal Height

Fundal height is the distance between the top of your uterus and your pubic bone. Healthcare providers use it to measure if fetal growth is on track. Your fundal height is measured beginning at about 20 weeks in pregnancy. If the fetus measures smaller or larger than average, an ultrasound may be needed to get a more accurate size.





Overview

Fundal height is the distance between your public bone and the top of your uterus (in centimeters) during pregnancy. It's used to see how the fetus is growing.

What is fundal height?

Fundal height is the distance between your pubic bone and the top of your uterus during pregnancy. Measuring fundal height helps healthcare providers assess if the fetus is developing correctly. It also can help determine gestational age (term to describe how far along the pregnancy is) and the fetus's position in your uterus. It's measured in centimeters with measuring tape. After about 20 weeks of pregnancy, your fundal height in centimeters should be close to the fetus's gestational age. For example, if you are 24 weeks pregnant, your fundal height should be around 24 centimeters.

When do doctors measure fundal height?

Your healthcare provider measures fundal height at each prenatal appointment beginning at about 20 weeks in pregnancy. This is the approximate time when fundal height and gestational age begin matching each other.

Test Details

How is fundal height measured?

Healthcare providers measure fundal height by locating your symphysis pubis and your fundus. Your symphysis pubis is a cartilage joint located between your pubic bones. The fundus is the top portion of your uterus. They may press down and feel around to find your fundus.

First, you will lay back on the exam table. Then, your healthcare provider will extend a paper or plastic tape measure from the top of your symphysis pubis (pubic bone) to your uterus (fundus). The distance between these two spots is your fundal height.

The location of your fundus moves as your pregnancy progresses. At about 12 weeks in pregnancy, your fundus is in almost the same spot as your pubic bone. By the time you reach 20 weeks, your fundus is at your belly button. This is about the time your fundal height and week of pregnancy begin to match one another.

At around 36 weeks, your fundus reaches your sternum or breastbone (the highest point it will reach). After 36 weeks, your fundal height can decrease. This can be because your baby has engaged into your pelvis to prepare for labor or for other reasons. Your provider may order additional tests to confirm there aren’t other causes for the decrease in fundal height.

How accurate is fundal height measurement?

Fundal height is one of the simplest and least invasive tools for tracking your baby's growth. It can be the first indication of growth problems or problems with your baby's position.

Your healthcare provider will order an ultrasound if your fundal height is concerning. Ultrasounds are more accurate at predicting your baby's size, but are only recommended two times during pregnancy (unless medically necessary).

Nothing is 100% accurate when it comes to estimating your baby's size in utero. It's common for your baby's size to be off by a centimeter or two. Your healthcare provider will do further testing if there is a reason to be concerned.

What does fundal height tell you about your baby?

Fundal height tells your healthcare provider important things about your baby's size, growth and position in your uterus. It helps confirm that your baby is growing as they should. It can also tell them how much amniotic fluid is in your uterus. Too little or too much amniotic fluid can indicate a problem.

Results and Follow-Up

What should fundal height be each week?

Your fundal height in centimeters should be close to the number of weeks you are in pregnancy, plus or minus 2 centimeters. However, this is only the case from about weeks 20 to 36. Before 20 weeks of pregnancy, your fundus is not high enough. After 36 weeks of pregnancy, your fundus starts to go down. This is because the fetus has dropped into your pelvis to prepare for labor. If this drop doesn't happen, this can indicate the fetus is breech.

For example, if you are 32 weeks pregnant, a fundal height of 30 to 34 centimeters is an acceptable size.

Does fundal height indicate baby size?

Yes, fundal height can help indicate fetal size. In addition to measuring fundal height, your healthcare practitioner will feel your abdomen to get an idea of the fetus's size and position in the uterus. It's important to remember that fundal height is just an estimate. If fetal size is a concern at any point in your pregnancy, your healthcare provider will recommend further testing.

When should I worry about my fundal height?

Your fundal height is usually not a reason for worry. It's OK for it to be off by at least two weeks or 2 centimeters. Your healthcare provider will review your medical history and decide if further tests are needed. It could simply be that your due date is wrong or that the fetus is slightly smaller or larger than average.

Does fundal height predict the due date?

Healthcare providers don't use fundal height to measure your due date. Fundal height is used to track how big or small the fetus is compared to its gestational age. The best way to determine your due date is to count 40 weeks (280 days) from the first day of your last menstrual period. Healthcare providers often use the first-trimester ultrasound to help determine gestational age and due date.

Additional Details

What does it mean if my fundal height is measuring small?

Some reasons why the fetus could be measuring small or behind for gestational age are:

  • You are petite or have strong abdominal muscles.
  • You have oligohydramnios (not enough amniotic fluid).
  • The fetus has already dropped into your pelvis.
  • Fetal growth restriction (several conditions can cause this).

If your healthcare provider is concerned about the fetus's size, they may order an ultrasound or additional tests to take a closer look.

What does it mean if my fundal height is measuring ahead?

Some reasons the fetus may measure ahead or large for gestational age are:

  • Your due date is wrong.
  • You have uterine fibroids.
  • You have a BMI of over 25 (have overweight or obesity).
  • You are carrying twins or triplets.
  • You have polyhydramnios (excess amniotic fluid).
  • The fetus is in a breech position.
  • The fetus has fetal macrosomia (it can be caused by diabetes).

Sometimes there is no cause and the fetus is just bigger than other fetuses the same age. Other times, your fundal height is large because your abdomen is overstretched from prior pregnancies or your bladder is full.

What is a normal fundal height after delivery?

Your uterus will go back to its pre-pregnancy size in about six weeks. At about an hour after childbirth, your fundus should be around your belly button (where it was at 20 weeks). After that, it should steadily decrease 1 centimeter every 24 hours. At about one week postpartum, your fundus should be at your pubic bone (where it was at 12 weeks). In most cases, by the time you return for your postnatal visit, your fundus has returned to its original location.

A note from Cleveland Clinic

Measuring your fundal height is one way your healthcare provider can make sure the fetus's growth is on track. If you're told the fetus measures ahead or behind schedule, try not to worry. It usually just means an ultrasound or further testing is needed. The fetus is more than likely developing perfectly. Talk to your healthcare provider if you have any concerns about your fundal height or the size of the fetus.

 


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