Fundal Height Measurement- Read All About It Here!

When pregnant, there will be a lot of things to take into consideration. You will have to have your general check-up along with a series of tests/scans done to assess the growth of your growing baby, one such test is measuring the fundal height.

So, what is this fundal height measurement?

The fundal height or the symphysis-fundal height (SFH) or the McDonald’s Rule measures the distance between the symphysis pubis and the top of uterine fundus.

Few things to know about the SFH measurement:

  • Useful after 20 weeks of pregnancy
  • SFH is most commonly measured by a measuring tape
  • The measurement estimated should closely match your gestation period (within 1- 2 centimeter)
  • The SFH increases as you progress through your pregnancy

Why is the fundal height so useful?

  •  It is an inexpensive method to monitor fetal growth in normal & uncomplicated pregnancies
  • A simple way to screen (the first step in the identification) fetal growth restriction (FGR) in a fetus after 20 weeks of gestation

How is fundal height estimated?

For you to understand how the fundal height is measured, you should know:

  • The fundal height chart: Fundal height is measured, estimated and recorded on a chart which contains the normal fundal height range. The values are marked based on the gestation period. The normal chart has two slopes marked on it, this marks the range of normal fundal height
  • The variables measured:
    • X-axis: gestation period in weeks
    • Y-axis: fundal height.

Using the fundal height chart, your doctor measures the fundal height. Depending on the location of the measured fundal height on the chart and the slope made, when compared to a previous measurement, the growth of the fetus can be determined (if it is regular or not).

The SFH compares the measurement of a particular pregnancy to a pre-made table and if the values deviate significantly, it mainly indicate:

Note: A rule of thumb that most follow is; the fundal height should coincide with the number of weeks pregnant (within 1- 2 centimeter). Eg: the fundal height measurement for week 19 of pregnancy should be between 17 to 21 centimeters. This is considered normal.

What happens if the fundal height values are skewed?

In normal cases, the fundal height should be within the predetermined values, if it isn’t then there is a reason to be concerned.  As if the values are either higher or lower then this can indicate an underlying problem.

More/larger fundal height aka measuring large fundal height:

The causes for an SFH measurement to be more than the normal include:

  • Multiple fetuses
  • Uterine fibroids
  • Loose abdominal muscles (early pregnancy symptom)
  • Excessive amniotic fluid
  • Wrong due date (confirmed by ultrasound)
  • Overweight causing error in reading
  • Breech/ any abnormal position of the baby
  • Extremely narrow pelvis
  • Large (macrosomia) large baby

Less/smaller fundal height aka measuring small fundal height:

The causes for an SFH measurement to be less than the normal include:

The reasons for a smaller fundal height could include:

  • Well developed abdominal muscles a
  • Wrong due date (confirmed by ultrasound)
  • Very little amniotic fluid
  • Growth restrictions in the uterus
  • Underweight causing error in reading
  • Baby has already dropped (to the pelvis)

This was a brief description of fundal height measurements. It should be known that SFH measurement is just a baseline assessment and needs a more accurate test for confirmation, most often being an ultrasound. It would be advisable to get as much information possible on the same from your doctor.

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Aishwarya

Dr. Aishwarya Rajeev has completed her MDS degree and is currently pursuing her PhD. She is an avid reader and loves to teach and write!

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