Fundal height is a measurement used during pregnancy to assess fetal growth and gestational age. It involves measuring the distance from the top of the pubic bone to the top of the uterus. This non-invasive screening tool helps monitor pregnancy progression and can indicate if further investigation is needed to ensure expected fetal development.
How Fundal Height is Measured
Healthcare providers perform fundal height measurements during prenatal appointments. The process usually begins around 20 weeks of pregnancy. The pregnant individual lies on their back with legs extended.
The provider first locates two specific anatomical landmarks. One landmark is the top of the pubic bone, also known as the symphysis pubis, which is a cartilage joint located between the pubic bones. The other landmark is the fundus, which is the uppermost, rounded part of the uterus. The provider may gently press on the abdomen to find the top of the uterus.
Once these points are identified, a flexible tape measure is used. The zero end is placed at the top of the pubic bone, and the tape is extended vertically over the abdomen to the top of the uterus. The measurement, recorded in centimeters, represents the fundal height. A full bladder can affect the measurement, so emptying the bladder beforehand is often recommended.
Understanding Your Fundal Height Measurements
Fundal height measurements provide insights into how the fetus is growing in relation to gestational age. From 20 to 36 weeks of pregnancy, fundal height in centimeters should roughly match the number of weeks of gestation. For instance, if you are 24 weeks pregnant, a fundal height measurement of around 24 centimeters is expected. A measurement within 2 to 3 centimeters, either above or below the gestational week, is considered normal.
This measurement serves as a screening tool, not a definitive diagnostic test. Other factors can influence the measurement without indicating a problem. These include the baby’s position within the uterus, the amount of amniotic fluid surrounding the baby, and the mother’s body type. For example, a baby in a breech position or a higher amount of amniotic fluid can lead to a larger measurement.
What Variations in Fundal Height Mean
When fundal height measurements deviate from the expected range, either measuring too high or too low, it prompts further assessment. A measurement that is larger or smaller than anticipated does not automatically indicate a problem with the baby or the pregnancy. The estimated due date might be slightly inaccurate. The mother’s body type, such as having a higher body mass index or looser abdominal muscles from previous pregnancies, can also influence the measurement.
A higher fundal height can be due to carrying multiple pregnancies (e.g., twins) or having an excess amount of amniotic fluid (polyhydramnios). Conversely, a lower fundal height might occur if the baby has settled deeper into the pelvis in preparation for birth, or if there is a lower amount of amniotic fluid (oligohydramnios).
Significant or consistent deviations from the expected range may lead healthcare providers to recommend additional investigations. An ultrasound is often the next step to assess fetal growth, the amount of amniotic fluid, and the baby’s position more precisely. This allows for a more detailed evaluation of the baby’s well-being. Fundal height is one piece of information in a comprehensive prenatal assessment, and an unexpected measurement warrants further evaluation rather than immediate concern.