Click on the links below.
The abdominal circumference is also used to plot growth and to see how the measurement grows throughout the pregnancy.
On the previous page was shown a 20 week pregnancy with an abdominal circumference of 15.86 cm. This can be plotted on the growth chart here. The measurement is just above the mean for 20 weeks.
The AC measurements can be plotted as the baby develops further:
You can see that the growth of the abdominal circumference does not exactly follow the curve of the chart. There are a number of reasons for this. There are variations of growth rate throughout pregnancy with growth spurts followed by periods when growth rates are not so rapid. In addition, it may be quite difficult to measure the abdomen accurately, for example, when it is partly obscured or distorted by adjacent structures as we shall see on the next few pages.
Remember that we are now considering fetal growth. We have already established gestational age at the first scan. The accuracy of gestational age diminishes as the pregnancy advances because there is greater variation in the size of babies as they get closer to term.
