Fundal Height – Significance and How to Measure

FUNDAL HEIGHT

There are many ways to check if your pregnancy is going according to the norm. Apart from checking your weight, ultrasounds, and your vitals, your doctor might also mention checking the fundal height. This is done in order to check the progress of the baby’s development and if the rate of development is normal.

What is Fundal Height?

Fundal height is used to measure the growth and development of the foetus after 20 weeks of pregnancy. It is the measurement from the top of the pubic bone to the top of the uterus. Fundal height in pregnancy is usually measured using a measuring tape. This measurement should match the gestation period within one to three centimetres. The fundal height or McDonald’s Rule will increase as your pregnancy progresses.

Importance of Fundal Height Measurement

If the mother does not showcase any factors for skewed fundal height measurement, then such a measurement could be indicative of the following factors:

  • Slow foetal growth
  • An abnormally large foetus
  • Too little amniotic fluid
  • Too much amniotic fluid

However, you must keep in mind that irregular fundal height is not always indicative of any significant issue with your pregnancy.

How to Measure Fundal Height?

Fundal height can be measured very easily. Here is a step by step procedure for measuring the fundal height.

Step One

It is best that you get the fundal height measurement done by your OB/GYN. This will give you the opportunity to discuss any irregularities in the measurement. So, the first step would be to visit your doctor.

Step Two

Make sure that you empty your bladder entirely before you step into your appointment to have the fundal height measured. Even a half-full bladder can cause a discrepancy in the fundal height measurements which can lead to unnecessary panic.

Step Three

You will be asked to change into a hospital gown as your regular clothes might influence the fundal height measurement.

Step Four

Your doctor will ask you to lie down as this will allow your doctor to measure the fundal height accurately.

Step Five 

Your doctor will ask you to breath slowly and steadily which ensures that there is not too much variation in your belly’s size and allows your doctor to gain an accurate reading.

Step Six

Your doctor will now measure the fundal height using a tape measure. The height is measured from the top of the uterus which will be in your stomach area to the top of the pubic bone which is in the pelvic region.

Step Seven

You can now change into your normal clothes and discuss the measurement with your doctor.

Step Eight

If there is any discrepancy in the fundal height measurement, then your doctor might ask for a series of investigative tests to find out the cause of the measurement. These tests might include an ultrasound. Your doctor might recommend that you get the tests done immediately or you could make an appointment for a later date.

 ULTRASOUND

What is Normal Fundal Height?

Fundal height is measured and recorded on a chart that also contains the normal fundal height range marked on it based on the gestation period. The fundal height chart by week has two variables: the X-axis marks the gestation period in weeks while the Y-axis marks the fundal height. The normal chart has two slopes marked on it to mark the range of normal fundal height. When your doctor measures your fundal height, she will mark the results on this chart. Depending on the location of the fundal height on the chart and the slope it creates when compared to the previous measurement, your doctor will be able to see if the growth of the foetus is regular or not. For example, the fundal height measurement for week 20 of the pregnancy should be between 18 to 22 centimetres. In fact, a rule of thumb that you can follow is that the fundal height should match the number of weeks that you have been pregnant with a couple of centimetres above and below as the normal range.

What Does Measuring Large For Gestational Age Mean?

The reasons for a larger fundal height could include:

  • Presence of uterine fibroids
  • Loose abdominal muscles probably due to an earlier pregnancy
  • Too much amniotic fluid
  • You could be carrying multiple foetuses
  • You have the wrong due date which will be confirmed by an ultrasound
  • Overweight women have a harder time getting an accurate reading
  • The foetus is in breach or any other abnormal position
  • The pelvis is much narrower than normal
  • The baby has macrosomia caused by gestational diabetes

What Does Measuring Small For Gestational Age Mean?

The reasons for a smaller fundal height could include:

  • Your abdominal muscles are well developed
  • Your due date has been calculated incorrectly
  • Too little amniotic fluid
  • The presence of intrauterine growth restrictions
  • You might be underweight
  • The baby might have already dropped to your pelvis

Fundal Height is a tool used to measure the growth and development of the foetus. It is usually a starting point to check for any irregularities which have to be confirmed by other investigative tests. Please consult with your doctor if you think that the fundal height does not fall within the normal range.