How to Measure Fundal Height and Fetus Size: Explained

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How to Measure Fundal Height

Table of Contents

As and when you progress in your pregnancy, you might often find yourself comparing the fetal growth from the top of the uterus via the abdomen to the size of a vegetable or fruit, as per the week size in the pregnancy app or through Parenthood bliss’s website. However, the doctor would help you with more accuracy to help ensure that the pregnancy is going as expected.

We understand that the progress might leave you being curious as to how the doctor measures the fundal height and the size all throughout your pregnancy. More importantly, what importance does it have to keep a check on the height measurement? If so, you have landed on the right article, as we are here to help you find answers to all these questions. Read on to discover!

Fundal Height Measurement: How To Measure Fundal Height During Pregnancy?

Fundal height measurements are done in centimeters from the pubic bone to the top of the uterus. This helps estimate the length and weight of the baby that the doctor then compares to the expected average fundal height to the average fundal height as per the week of the trimester.

However, as measuring the exterior of the uterus isn’t a precise science, it’s okay if the fundal height doesn’t match or measure up with the estimated due date.

When And How Do Doctors Measure The Fundal Height By Week In Utero At The Gestational Age?

The simplest way followed by the doctors to measure the baby’s size in the utero is by measuring the expecting mom’s fundal height, which means, the distance between the pubic bone to the top of your uterus in centimeters (Symphysis fundal height). You may also expect the doctor to palpate the abdomen to get an idea about the baby’s size.

For instance, post 24 weeks in the pregnancy, the fundal height in centimeters would be roughly equivalent to the week of gestation. Like, if 29 weeks pregnant, the fundal height would probably be 29 in centimeters.

However, the measurement of the fundal height starts to decrease between weeks 37 and 40, as the baby begins to descend into your pelvis, preparing for birth.

On the other hand, transvaginal and transabdominal ultrasounds are the other ways to measure the fundal height more accurately. In this ultrasound, a wand sends sound waves that in turn bounce off of the baby, producing an image you see on screen. Here, a sonographer will take the measurements used to estimate the baby’s weight via a computerized algorithm.

You might wonder, when does a practitioner start measuring the baby? The measurement starts around 20 weeks of pregnancy and in every prenatal appointment until the birth of your little one.

In the first trimester, the use of ultrasound is to estimate the due date via the measurement from the baby’s crown-to-rump length, or from the top of the head to the bottom. Otherwise, by the third trimester, the ultrasound helps measure the parts of the baby, size, and weight, ensuring a healthy pregnancy as expected.

Note – Ultrasounds are usually accurate, plus or minus 2 centimeters over-or under by 10 to 20 percent in rare cases that lead to unnecessary interventions like C-sections. Also, make sure you do not indulge in unnecessary ultrasounds irrespective of how safe they might be.

How Accurate Is The Fundal Height By Week? Is It Relatively Small For The Gestational Age?

Mostly no! Estimating the fundal height in utero is the best and the simplest way to know the baby’s size based on averages. Measuring larger than expected or smaller than the average is completely normal as the body mass index of the expecting moms varies.

Perhaps, according to the American College of Obstetricians, the fundal height measurements in non-obese women are often off by two weeks. There’s always a margin of error when the doctors match the number while estimating the exact weight and size of the baby. They could be off by a pound or even more, and a centimeter or two bigger or smaller.

This inaccuracy in measuring the fundal height could be less accurate, including the position and volume of the amniotic fluid, by a week or two in women who are obese or have a history of uterine fibroids. It doesn’t always mean intrauterine growth.

Fundal Height Measurement: What To Expect If The Doctor Measures It To Be Either Big Or Small?

Surely, getting results of the baby’s fundal size to be relatively similar to the gestational age helps to ensure that the pregnancy is on track and as expected. However, if there is a difference in the fundal height of more than three weeks during your trimester, the doctor will for sure look into it.

Mostly, in these readings, the cases turn out to be harmless as the due dates are wrongly estimated. The health care practitioners usually estimate the due date from the first day of the last menstrual period, but there are chances that the conception took place earlier or later.

Also, the results that turn out to be larger or smaller than expected could indicate other conditions too. For instance, small measurements could mean that there isn’t much amniotic fluid or intrauterine growth restriction. On the other hand, larger measurements may be a sign of way too much amniotic fluid, uncontrolled gestational diabetes, or a uterine fibroid. If either is suspected, there could be an extra ultrasound or the pregnancy will be monitored closely to prevent any foreseen dangers to either you or the baby. 

That’s all about the fetal fundal height and ways to measure it. However, while we speak of the growth of the baby, you might want to keep track of the fetal movement and kick counts in your trimester for a better understanding of the baby’s health.

How To Measure Fundal Height Final Conclusion:

The benefit of measuring the size of the baby in the utero helps with a rough estimate and understanding of the pregnancy. However, these measurements aren’t quite accurate and could in a few cases be two or three weeks off, but work as a guide to the care you receive. Also, visiting the doctor in all prenatal appointments helps in a healthy pregnancy and delivery.

How to measure the Fundal Height FAQs:

1) Does Fundal height correlate with Baby Size ?

Generally, the fundal height measurement is taken from the distance of the pubic bone to the top of the uterus in centimeters or, the doctor will palpate the abdomen to get an idea of the baby's size. This by the 24th week of pregnancy correlates with the fundal height to the expected week of gestation.

2) How do you measure Fundal height in pregnancy ?

These fundal heights are measured by the doctor via ultrasound while you lay flat on your back. The height is measured in centimeters. Or, the doctor would make use of a measuring tape to see the distance from your pelvis to the top of the uterus.

3) What is more accurate, the Fundal height or ultrasound ?

Irrespective of the ultrasound examination giving out a better diagnostic value result, the fundal heights of the birth weight are abnormal.
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