Fundal height: An accurate indicator of fetal growth?

Fundal height, the distance from the top of the uterus to the pubic bone measured in centimeters, usually matches closely to the number of weeks you've been pregnant. For example, if you are 25 weeks pregnant, your physician would expect your fundal height to be about 25 centimeters.

However, I wouldn't be concerned about having a fundal height two centimeters larger than expected. A two-centimeter variance is not unusual and can be caused by many factors that do not imply a problem for your baby:

• Your uterus might be thicker than average.
• Your abdominal wall may increase the measurement a bit.
• Your baby may be in a breech position.
• You might be carrying a larger, but perfectly healthy baby.

Of course, if the measurement continues to increase faster than expected, your doctor may suspect:

• Rapid growth of the fetus (macrosomia) due to gestational diabetes
• Excessive amniotic fluid (polyhydramnios), which may indicate a problem with the baby or the pregnancy

Your doctor may order an ultrasound to assess the cause. A multiple pregnancy also would be considered.

It's also common for pregnant women to have a fundal height that is a few centimeters smaller than expected. This could be due to:

• A very slim frame or well-conditioned abdominal muscles
• Tall stature with a straight back, so the uterus doesn't protrude forward as much as in average-height women
• A smaller, but perfectly healthy baby

Similarly, if you were measuring much smaller than expected for the number of weeks you've been pregnant, or if the measurement continues to increase at a slower rate than expected, your doctor may suspect:

• There is too little amniotic fluid surrounding your baby (oligohydramnios), which may indicate a problem with the baby or the pregnancy.
• Your baby is growing at a slower rate than expected, a condition called intrauterine growth restriction.

An ultrasound is often used to help your doctor determine the cause.