Which rule relates the age of a fetus to its length for estimating growth?

Morrison's rule is a guideline used in forensic medicine and obstetrics to estimate the age of a fetus based on its length. This rule emphasizes a correlation between fetal growth and gestational age, allowing practitioners to estimate the age of the fetus in weeks by measuring its length, typically through the crown-rump length (CRL) during the first trimester or through other measurements in later stages of pregnancy.

Morrison’s rule is particularly useful in clinical scenarios where determining the gestational age is critical, such as in cases of suspected fetal growth restriction or assessing viability. By establishing a reliable relationship between age and length, Morrison's rule aids in making informed medical and legal decisions regarding pregnancy.

The reference to other rules in the question is important for context, but these would not apply in the same manner as Morrison's rule when it comes to relating fetal length to age for estimating growth. Each of those rules either addresses different aspects of fetal development or is applicable in contexts outside of this specific measurement.