2008 ICD-9-CM Volume 1 Diagnosis Codes Home > Certain Conditions Originating In The Perinatal Period 760-779 > Other Conditions Originating In The Perinatal Period 764-779 > Disorders Relating To Long Gestation And High Birthweight 766.* > 2008 ICD-9-CM Diagnosis 766.21 Post-term infant  On October 1, 2008 the 2009 ICD-9-CM codes came into effect. Therefore, this code may be out of date. The 2009 version of ICD-9-CM 766.21 can be accessed here. An infant born at or after 42 weeks of gestation. 766.21 is a specific code that can be used to specify a diagnosis 766.21 contains 4 index entries View the ICD-9-CM Volume 1 766.* hierarchy ICD9Data's sister site ProcedureCodes.com launches with the 2008/09 CPT® codes - read more on the ICD9Data.com blog. 766.21 also known as: Infant with gestation period over 40 completed weeks to 42 completed weeks Index entries containing 766.21: Hypermaturity (fetus or newborn) post-term infant 766.21 Infant - see also condition post-term (gestation period over 40 completed weeks to 42 completed weeks) 766.21 Late - see also condition infant post-term (gestation period over 40 completed weeks to 42 completed weeks) 766.21 Post-term (pregnancy) 645.1 infant (gestation period over 40 completed weeks to 42 completed weeks) 766.21