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What is Fundal Height?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

Fundal height is a measurement which can be taken during pregnancy to assess the growth of the fetus and the development of the pregnancy. It is done by measuring from the pubic bone to the top of the uterus, and is usually recorded in an expecting mother's chart. Historically, fundal height was one of the few ways to gauge the development of the pregnancy. Today, other measures are available and they tend to be more accurate, but they aren't as fast, and they can be costly.

The only tool needed for a fundal height measurement is a tape measure. The height is usually measured in centimeters, and at around the 20th week of pregnancy, the measurement should start to correspond with the number of weeks in the pregnancy. A woman at 27 weeks, for example, should have a fundal height of 27 centimeters (about 10.6 inches). As the pregnancy progresses and the uterus expands, the top of the uterus will continue to move up to make room for the growing baby.

A fundal height measurement can be found with a tape measure.
A fundal height measurement can be found with a tape measure.

A number of things can interfere with a fundal height measurement. Sometimes it is done incorrectly, causing disparities in week to week measurements. If a woman has a full bladder, the measurement may be off. Likewise if she has thick uterine tissue, has had a C-section, or is carrying twins. Not all babies follow a growth chart perfectly either, so being slightly off is not a cause for concern. Finally, in the last few weeks of pregnancy, the fetus starts to descend, causing the fundal height to shrink.

An ultrasound can provide accurate fundal height.
An ultrasound can provide accurate fundal height.

However, if the fundal height is extremely off from the estimated age of the pregnancy or it fails to progress, it can be a sign that there is a problem. The fetus may be getting too big, or may not be growing enough as a result of medical complications. Twins or multiples can also cause a skew in the fundal height. If a woman's pregnancy appears to be failing to progress as expected, a doctor may recommend diagnostic tests and additional measurements to learn more about what is going on.

As a pregnancy progresses and the uterus expands, the top of the uterus will continue to move up to make room for the growing baby.
As a pregnancy progresses and the uterus expands, the top of the uterus will continue to move up to make room for the growing baby.

McDonald's Rule, as fundal height is sometimes known, can be a valuable tool for quickly assessing the development of a pregnancy at no cost. Experienced providers can even do measurements without a tape, using their fingers as a guideline to see how much the uterus has grown. For more accurate information, ultrasound needs to be used to image the uterus and see how it has grown.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a WiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a WiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...

Discussion Comments

Esther11

I think that ultra sound equipment was one of the most useful medical procedures ever invented. In taking care of the pregnant women and fetus,it is indispensable.

Several decades ago, is all the doctor could do for measuring fundal height was to measure with a tape. In the majority of cases, this type of measurement was enough, but in the case of twins, or failure of a fetus to grow enough, there were no ultrasounds to refer to.

An interesting observation - after the 20 week mark, babies fundal height corresponds closely with the weeks of pregnancy.

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    • A fundal height measurement can be found with a tape measure.
      By: Schlierner
      A fundal height measurement can be found with a tape measure.
    • An ultrasound can provide accurate fundal height.
      By: Andrey Chmelyov
      An ultrasound can provide accurate fundal height.
    • As a pregnancy progresses and the uterus expands, the top of the uterus will continue to move up to make room for the growing baby.
      By: Valua Vitaly
      As a pregnancy progresses and the uterus expands, the top of the uterus will continue to move up to make room for the growing baby.
    • A fundal height measurement will help assess the growth and development of a fetus.
      By: Noel Powell
      A fundal height measurement will help assess the growth and development of a fetus.
    • Vaginal ultrasound probes may be inserted into the vagina during pregnancy to obtain an image of the uterus.
      By: zayacsk
      Vaginal ultrasound probes may be inserted into the vagina during pregnancy to obtain an image of the uterus.
    • The fundal height measurement of a woman who has had a C-section may not be accurate.
      By: Jorge Abdala
      The fundal height measurement of a woman who has had a C-section may not be accurate.
    • Fundal height is the measurement from the pubic bone to the top of the uterus.
      By: reineg
      Fundal height is the measurement from the pubic bone to the top of the uterus.