Fundal height is generally defined as the distance from the top of the uterus to the pubic bone measured in centimeters. After the first 12 weeks of pregnancy, your fundal height measurement often matches the number of weeks you've been pregnant. For example, if you're 27 weeks pregnant, your health care provider would expect your fundal height to be about 27 centimeters. It isn't unusual, however, to measure somewhat smaller or larger than expected.
This might happen if you:
- Have a tall or slim frame
- Have a short or heavy frame
- Have a full bladder
- Are carrying twins or other multiples
In other cases, fundal height that measures smaller or larger than expected — or increases more or less quickly than expected — could indicate conditions such as:
- Slow fetal growth (intrauterine growth restriction)
- Rapid fetal growth (macrosomia)
- Too little amniotic fluid (oligohydramnios)
- Too much amniotic fluid (polyhydramnios)
- Uterine fibroids
- A baby prematurely descending into the pelvis or settling into a breech or other unusual position
Depending on the circumstances, your health care provider might recommend an ultrasound or other tests to determine what's causing the unusual measurements.
Remember, fundal height is only a tool for gauging fetal growth and gestational age — it's not an exact science. Typically, fundal height measurements offer reassurance of a baby's steady growth. If you're concerned about your fundal height measurements, ask your health care provider for details.