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Fundal height, or McDonald's rule, is a measure of the size of the uterus used to assess fetal growth and development during pregnancy. It is measured from the top of the mother's uterus to the top of the mother's pubic bone in centimeters.
|Gestational age||Fundal height|
|40 weeks||1-2 finger widths below subcostal arch|
|36 weeks||At costal arch|
|32 weeks||Between umbilicus and xiphoid process|
|28 weeks||3 finger widths above umbilicus|
|24 weeks||At umbilicus|
|20 weeks||3 finger widths below umbilicus|
|16 weeks||3 finger widths above symphysis|
It should match the fetus' gestational age in weeks within 1 to 3 cm, e.g., a pregnant woman's uterus at 26 weeks should measure 23 to 29 cm. This is valid from 24 weeks.
Most caregivers will record their patient's fundal height on every prenatal visit. Measuring the fundal height can be an indicator of proper fetal growth and amniotic fluid development.
Knowledge of gestational age may impact how the height is measured.
A shorter measure can happen for one of the following reasons:
On the other side, a longer measure can be caused by:
As a pregnancy approaches its end, the fundal height will become less accurate.
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