Haase rule

Haa·se rule

(hahs),
the length of the fetus in centimeters, divided by 5, is the duration of pregnancy in months, that is, the age of the fetus.

Haa·se rule

(hah'sĕ rūl)
The length of the fetus in centimeters, divided by 5, is the duration of pregnancy in months, i.e., the age of the fetus.