diff --git a/Sql Server/OMOP CDM ddl - SQL Server.sql b/Sql Server/OMOP CDM ddl - SQL Server.sql
index 88eb0da..928e19e 100644
--- a/Sql Server/OMOP CDM ddl - SQL Server.sql	
+++ b/Sql Server/OMOP CDM ddl - SQL Server.sql	
@@ -254,9 +254,7 @@ 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		DATETIME2		NOT NULL ,
   observation_period_end_date		DATE		NOT NULL ,
-  observation_period_end_datetime		DATETIME2		NOT NULL ,
   period_type_concept_id				INTEGER		NOT NULL
 )
 ;