<prompt> What is the purpose of using Hasses formula in pregnancy?Estimate fetal ageIdentify fetal blood groupIdentify fetal sexIdentify fetal congenital malformations  <response>: Hasses rule is employed in calculating the age of fetus by its length. During first five months of pregnancy, the length in cms is square of the age in months. During the second five months of pregnancy, length in cms divided by 5 gives age in months. Ref: Textbook of forensic medicine and toxicology by Krishan Vij, 3rd edition, Page 558. 