What Is Fundal Height?
Medically reviewed by Chioma Ndubisi, MD
Fundal height is a measurement taken during pregnancy to monitor fetal growth. Fundal height measures the distance between the top of the uterus and the pelvic bone in a pregnant person. It determines if your baby is growing as expected and confirms gestational age (how far along you are in pregnancy). It can also assess where the baby is in the uterus.
This article discusses fundal height, including what it is, when it's used, and what the measurements mean during pregnancy.
Fundal Height Defined
Fundal height is a simple screening tool your healthcare provider uses to monitor your baby’s growth and development. It is measured in centimeters and is often first taken at prenatal appointments starting at 20 weeks of pregnancy. The fundal height measurement in centimeters should be close to the fetus’s gestational age in weeks. For example, if you are 27 weeks pregnant, your fundal height should be about 27 centimeters (give or take 2 centimeters).
A fundal height that is too small or too large could indicate a pregnancy complication. If your fundal height is out of the norm, your healthcare provider will recommend an ultrasound. People with high-risk pregnancies often require more ultrasounds as well.
Fundal height is an imprecise measurement, and some factors can affect it. For instance, fundal height may be more challenging to measure in pregnant people who have a body mass index (BMI) of 30 or higher. Having a history of uterine fibroids may also affect the accuracy of fundal height.
Average fundal height in centimeters usually is the same numeral as the fetus's gestational age in weeks. For example, if you are 32 weeks pregnant, your fundal height will likely be 32 centimeters.
How Fundal Height Measurements Work
Fundal height can be measured quickly and easily. Your healthcare provider will ask you to lie down face up on the exam table, similar to when you have an ultrasound or pelvic exam.
Your provider will then run a soft tape measure from the area of your belly where the top of your uterus would be down to your pubic bone.
After 20 weeks of pregnancy, your fundal height will likely be measured at each appointment. Before 20 weeks, an ultrasound exam estimates your baby’s gestational age. If your fundal height measurement is higher or lower than expected, your provider will likely remeasure you and then refer you for an ultrasound.
What Are Fundal Height Measurements Used For?
Measuring fundal height is used to monitor fetal growth and development. Several factors can affect how a fetus develops during pregnancy. Fundal height is a simple way to detect potential growth issues or complications.
If your fundal height is low, your baby may not be growing as expected. If your fundal height is high, your baby may grow faster than expected. When your fundal height measurement is below or above average, your healthcare provider will recommend an ultrasound to confirm the finding and determine the cause.
Genetics, nutrition, infection, environmental exposures, and the pregnant person’s overall health influence fetal size and growth.
Small for Gestational Age
"Small for gestational age" is a term that refers to a fetus that is smaller or less developed than usual. This is also referred to as intrauterine growth restriction. Babies with a birth weight below the 10th percentile are considered small for gestational age.
If your fundal height is smaller than expected, your baby may be small for gestational age. It is also possible that you are not as far along in pregnancy as previously estimated.
Possible causes of being small for gestational age include:
Metabolic diseases (medical conditions caused by a genetic defect)
Chromosome anomalies (a change in a baby's DNA that alters development before birth)
Multiple pregnancy (twins, triplets, etc.)
Infants who are small for gestational age are at higher risk of experiencing:
High red blood cell count
Hypoglycemia (low blood sugar)
Meconium aspiration (when a newborn breathes meconium or stool and amniotic fluid into the lungs)
Large for Gestational Age
"Large for gestational age" is a term referring to a fetus larger or more developed than average. Babies with a birth weight above the 90th percentile are considered large for gestational age.
If your fundal height exceeds the average, your baby may be large for gestational age. You may also be further along in pregnancy than previously estimated.
Possible causes of large gestational age include:
Excessive pregnancy weight gain
Babies who are born large for gestational age are at a higher risk of experiencing:
An injury during childbirth
Shoulder dystocia (when a baby's shoulders get stuck during delivery)
Low blood sugar after delivery
Neonatal intensive care unit (NICU) admission
Risks and Warnings
A fundal height measurement is a noninvasive tool. There is no risk associated with this exam. It is important to note that fundal height is not always accurate and may vary depending on the healthcare provider’s technique, the pregnant person’s weight gain, and other factors.
For this reason, it is important to verify any abnormal findings with an ultrasound immediately. Research estimates that 75% to 90% of fetal growth abnormalities go undiagnosed until birth.
Fundal height is a measurement taken during pregnancy to monitor fetal growth. Fundal height measures the distance between the pelvic bone and the top of the uterus in a pregnant person. It determines if your baby is growing as expected.
Fundal height is measured in centimeters and is usually started around 20 weeks of pregnancy. It may be used to assess your baby for small or gestational age (SGA) or large for gestational age (LGA). If your measurement is abnormal, your provider will recommend an ultrasound exam.