diff --git a/PostgreSQL/OMOP CDM ddl - PostgreSQL.sql b/PostgreSQL/OMOP CDM ddl - PostgreSQL.sql
index 8229cc2..396e29e 100644
--- a/PostgreSQL/OMOP CDM ddl - PostgreSQL.sql	
+++ b/PostgreSQL/OMOP CDM ddl - PostgreSQL.sql	
@@ -254,10 +254,8 @@ CREATE TABLE observation_period
      observation_period_id				INTEGER		NOT NULL , 
      person_id							INTEGER		NOT NULL , 
      observation_period_start_date		DATE		NOT NULL , 
-     observation_period_start_datetime		TIMESTAMP		NOT NULL ,
      observation_period_end_date		DATE		NOT NULL ,
-     observation_period_end_datetime		TIMESTAMP		NOT NULL ,
-	 period_type_concept_id				INTEGER		NOT NULL
+     period_type_concept_id				INTEGER		NOT NULL
     ) 
 ;