Symphysis Fundal Height (SFH)
Measuring fundal height during pregnancy
Your doctor may regularly measure your fundal height throughout pregnancy, which is the distance between your pubic bone and the top of your uterus. One approach to monitor your baby's development is through this screening.
Fundal height: what is it?
The distance between the top of your uterus (fundus) and your pubic bone (symphysis pubic) is known as your fundal height. A quick and low-cost way to make sure your kid is growing properly is to measure their fundal height. Your doctor will probably use ultrasounds to follow your baby instead of fundal height measures if your pregnancy is deemed high-risk.
Your last menstrual cycle and your initial ultrasound examination will be used to determine your due date, so keep that in mind if you are having your fundal height assessed. However, it can tell you how much amniotic fluid is in your uterus and how big your baby is. (While it is rare, having too much or too little amniotic fluid might increase your risk of problems.)
The fundal height measurement is one method of screening for pregnancy issues, however it is not a diagnostic tool (you wouldn't receive treatment based on a measurement that is inaccurate).
As your pregnancy goes on, your measurement of fundal height varies. A variety of normal fundal height measures during pregnancy are as follows:
- The fundus is level with the pubic bone at 12 weeks.
- It is located around midway between the pubic bone and the umbilicus, or belly button, at 16 weeks.
- It reaches the belly button about 20 weeks.
- Starting at 24 weeks, the measurement in centimeters should correspond to your baby's gestational age, within a centimeter or two in each direction. Therefore, your fundal height should be between 23 and 27 cm if you are 25 weeks pregnant.
- As the baby engages in your pelvis (moves down) in preparation for birth, the fundal height may drop after 36 weeks.
Your uterus will descend to its location at 20 weeks, which is around your belly button, approximately one hour after delivery. It will then gradually regain its typical size in around six weeks.
Who will be measured for fundal height?
For women with low-risk pregnancies, fundal height measures are typically done at every prenatal appointment starting around week 24.
Fundal height measures are often not performed on women who are being evaluated for a high-risk pregnancy (those with high-risk illnesses including obesity, lupus, diabetes, and hypertension). This is due to the fact that they will probably have ultrasounds to track the development of their unborn child during pregnancy. For these ladies, measuring the fundal height is not essential because ultrasounds are a more accurate way to evaluate a baby's growth.
What influences measures of fundal height?
Fundal height measures can be influenced by a variety of factors, but remember that there aren't always explanations for why someone's measurement is less or greater than anticipated. In order to determine what's happening and to confirm your due date, your physician will likely arrange an ultrasound; however, following a little or big fundal height measurement, the ultrasound is often normal.
If your fundal height is more than 3 cm higher than what is typical for your stage of pregnancy, depending on your due date, you are said to be measuring large for gestational age. Your measurements may be excessive for your gestational age if:
- Your due date has passed. (Your provider can determine a more precise due date with the use of the ultrasound.)
- Perhaps because of previous pregnancies, your abdominal muscles are looser than those of other women.
- You may find it more challenging to obtain an accurate measurement if you are overweight or obese.
- You have fibroids in your uterus.
- You have twins or more in your womb.
- You have polyhydramnios, or too much amniotic fluid.
- Your infant is in an abnormal position, such as breech.
- The disorder known as macrosomia is when your infant is significantly larger than usual. Pregnancy-related type 1 or type 2 diabetes and gestational diabetes are risk factors for macrosomia.
Your fundal height is more than three centimeters below what is typical at your stage of pregnancy if you measure small for gestational age. Additionally, your fundal measurement may be tiny if:
- Your body is tiny, and your abdominal muscles are well-developed.
- In anticipation of delivery, your baby has fallen into your pelvis.
- There is intrauterine growth limitation in your baby.
- Your amniotic fluid (oligohydramnios) is insufficient.
How a provider measures fundal height
Using a measuring tape, the fundal height is measured in millimeters.
You will be asked to lie flat on your back by your provider. The measuring tape will be stretched lengthwise over your abdomen to the top of your uterus after one end is placed on your pubic bone. Your fundal height is the measurement at which the tape reaches the top of your uterus.
How to take your own measurements of fundal height
Even for seasoned practitioners, obtaining an exact fundal height figure can be challenging. However, there's no harm in trying, provided you don't place too much trust in it. Here's how:
- On your back, lie flat.
- Position the zero at your pubic bone using a tape measure that has centimeters marked on it.
- Pull the tape toward the top of your uterus, above (and flat against) your stomach. Your fundal height is the measurement at which the tape reaches the top of your uterus, which is the hardest part of the belly where you can press your hand down.
Should my measurement of fundal height worry me?
If your measurement of fundal height is wrong by a centimeter or two, don't panic; this is normal and shouldn't disturb you. This approach isn't precise, and it's possible for measurements to be somewhat off.
However, one screening method your doctor may do to ensure your pregnancy is healthy and your baby is growing well is measuring your fundal height. Your obstetric history and other variables will also be taken into account by your provider. They will immediately arrange an ultrasound to assess the amount of amniotic fluid and the growth of your baby if they have any worries about your measurement. As your pregnancy goes on, you may also require further monitoring.
