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Compare your fundal height measurement to expected values and assess fetal growth during pregnancy.
Measured from top of pubic bone to top of uterus (fundus)
Current weeks of pregnancy
Fundal height is the distance from the top of your pubic bone to the top of your uterus (called the fundus), measured in centimeters. This simple, non-invasive measurement is taken at each prenatal visit starting around 20 weeks of pregnancy to monitor fetal growth and development. Healthcare providers use a measuring tape to assess whether the baby is growing appropriately for gestational age. After 20 weeks, fundal height in centimeters typically corresponds closely to gestational age in weeks, give or take 2 centimeters. For example, at 28 weeks pregnant, fundal height should measure approximately 26-30 cm.
Fundal height measurement serves as a screening tool to identify potential growth issues. Measurements significantly larger or smaller than expected may indicate conditions requiring further investigation through ultrasound. A fundal height larger than expected could suggest a larger baby (macrosomia), twins or multiples that weren't previously detected, excess amniotic fluid (polyhydramnios), or uterine fibroids. Conversely, measurements smaller than expected might indicate intrauterine growth restriction (IUGR), low amniotic fluid (oligohydramnios), the baby being in a different position, or incorrect dating of the pregnancy. While fundal height is a useful screening tool, it's not diagnostic, and ultrasound provides more detailed and accurate assessment of fetal growth when concerns arise.
Fundal height is measured during prenatal appointments with the pregnant person lying on their back with an empty bladder (a full bladder can affect measurement accuracy). The healthcare provider locates the top of the pubic bone and the fundus (top of the uterus) by gently palpating the abdomen. Using a flexible, non-stretch measuring tape, they measure the distance between these two points in centimeters. The measurement is taken from the same reference points each time to ensure consistency. This measurement typically begins around 20 weeks when the fundus rises above the pelvic bone and becomes easier to palpate.
The general rule after 20 weeks is that fundal height in centimeters equals gestational age in weeks, plus or minus 2 centimeters. This formula (fundal height ≈ gestational age ± 2 cm) provides a quick reference for expected growth. For example, at 32 weeks, fundal height should measure between 30-34 cm. Measurements within this 4-cm range (2 cm above or below) are considered normal. However, several factors can affect fundal height measurements including maternal body type (obesity can make measurements less accurate), baby's position, amount of amniotic fluid, multiples, and even the experience of the person taking the measurement.
If fundal height measurements are consistently outside the expected range or show sudden changes, your healthcare provider will likely order an ultrasound for detailed evaluation. Ultrasound can measure specific fetal parameters including head circumference, abdominal circumference, and femur length to calculate estimated fetal weight and assess growth patterns more precisely. It's important to remember that fundal height is just one tool among many for monitoring pregnancy health. Fetal movement, maternal weight gain, urine tests, blood pressure, and periodic ultrasounds all contribute to comprehensive prenatal care. Don't be alarmed by a single abnormal measurement; trends over multiple visits are more significant than individual readings.
| Weeks Pregnant | Expected Fundal Height | Normal Range | Fundal Location |
|---|---|---|---|
| 12 weeks | ~12 cm | 10-14 cm | At pubic bone |
| 16 weeks | ~16 cm | 14-18 cm | Halfway to navel |
| 20 weeks | ~20 cm | 18-22 cm | At navel (belly button) |
| 24 weeks | ~24 cm | 22-26 cm | 2 fingers above navel |
| 28 weeks | ~28 cm | 26-30 cm | Halfway to sternum |
| 32 weeks | ~32 cm | 30-34 cm | Between navel and sternum |
| 36 weeks | ~36 cm | 34-38 cm | Just below sternum/ribs |
| 40 weeks | ~37-40 cm | 35-40 cm | May drop as baby descends |
| Factor | Effect on Measurement | Clinical Significance |
|---|---|---|
| Maternal obesity | Less accurate measurement | Ultrasound more reliable |
| Twins/Multiples | Larger than expected | Usually detected early by ultrasound |
| Baby's position | Can vary measurement | Breech or transverse may measure differently |
| Amniotic fluid | Too much (poly) or too little (oligo) | Requires ultrasound evaluation |
| Uterine fibroids | May increase measurement | Usually known from earlier ultrasounds |
| Full bladder | Artificially increases height | Empty bladder before measurement |
One measurement outside the normal range doesn't automatically indicate a problem. Your provider looks at trends over multiple visits. Baby's position, recent meals, and bladder fullness can all affect measurements.
Regular fundal height measurements at each visit help track growth patterns. Consistent monitoring allows early detection of growth issues and ensures timely intervention if needed.
If fundal height raises concerns, ultrasound offers detailed fetal measurements including estimated weight, amniotic fluid levels, and growth velocity. This provides much more information than fundal height alone.
Fundal height is less accurate in women with obesity, very athletic builds, or short stature. Your provider may rely more heavily on ultrasound for growth monitoring in these cases.
Contact your provider immediately if you notice decreased fetal movement, sudden swelling, severe headaches, or vision changes, regardless of fundal height measurements. These may indicate serious complications.
In the last few weeks before delivery, fundal height may not increase or may even decrease slightly as the baby descends into the pelvis (lightening). This is normal and doesn't indicate a problem.
Fundal height is typically measured starting around 20-24 weeks of pregnancy when the uterus rises above the pelvic bone and becomes easier to measure. Before this, the uterus is still within the pelvis, making accurate measurement difficult.
Small measurements may indicate IUGR (intrauterine growth restriction), low amniotic fluid, incorrect dating, or baby in a different position. Your provider will order an ultrasound to investigate. Many times, measurements are off due to positioning or dating, not actual growth issues.
Large measurements may suggest a larger baby (macrosomia), twins/multiples, excess amniotic fluid (polyhydramnios), gestational diabetes, or incorrect dates. An ultrasound will clarify. Many larger measurements are simply due to a healthy, bigger baby.
No, fundal height is not used for dating pregnancy. Early ultrasound (before 13 weeks) is the most accurate method for establishing due dates. Fundal height is only used to monitor ongoing growth, not to calculate conception or due dates.
While you can try, it's difficult to get accurate measurements on yourself. The measurement requires identifying specific anatomical landmarks and keeping the tape straight, which is challenging when you're pregnant. Leave measurements to your healthcare provider.
Yes, how you "carry" your baby can affect fundal height measurements. Women who carry high may measure larger, while those who carry low may measure smaller, even with normally growing babies. This is one reason trends matter more than single measurements.
No, fundal height only provides a rough estimate of appropriate growth. It cannot predict exact birth weight. Even detailed ultrasound estimates can be off by a pound or more. Fundal height is a screening tool, not a precise measurement.
Your provider will order serial ultrasounds to track fetal growth over time, possibly check amniotic fluid levels, and may recommend NST (non-stress tests) or BPP (biophysical profile) to ensure baby is thriving. Close monitoring ensures early detection of any issues.
This calculator is for educational and informational purposes only and should not replace professional medical advice. Fundal height is a screening tool, not a diagnostic test. Always discuss your measurements and any concerns with your healthcare provider. Abnormal measurements require professional evaluation, typically including ultrasound for detailed assessment.