diff --git a/Impala/OMOP_Parquet_v5.2.sql b/Impala/OMOP_Parquet_v5.2.sql
index 944b385d..e82cc965 100644
--- a/Impala/OMOP_Parquet_v5.2.sql
+++ b/Impala/OMOP_Parquet_v5.2.sql
@@ -158,9 +158,7 @@ SELECT
  observation_period_id,
  person_id,
  TO_UTC_TIMESTAMP(CONCAT_WS('-', SUBSTR(CAST(observation_period_start_date AS STRING), 1, 4), SUBSTR(CAST(observation_period_start_date AS STRING), 5, 2), SUBSTR(CAST(observation_period_start_date AS STRING), 7, 2)), 'UTC') AS observation_period_start_date,
- TO_UTC_TIMESTAMP(CONCAT_WS('-', SUBSTR(CAST(observation_period_start_date AS STRING), 1, 4), SUBSTR(CAST(observation_period_start_date AS STRING), 5, 2), SUBSTR(CAST(observation_period_start_date AS STRING), 7, 2)), 'UTC') AS observation_period_start_datetime,
  TO_UTC_TIMESTAMP(CONCAT_WS('-', SUBSTR(CAST(observation_period_end_date AS STRING), 1, 4), SUBSTR(CAST(observation_period_end_date AS STRING), 5, 2), SUBSTR(CAST(observation_period_end_date AS STRING), 7, 2)), 'UTC') AS observation_period_end_date,
- TO_UTC_TIMESTAMP(CONCAT_WS('-', SUBSTR(CAST(observation_period_end_date AS STRING), 1, 4), SUBSTR(CAST(observation_period_end_date AS STRING), 5, 2), SUBSTR(CAST(observation_period_end_date AS STRING), 7, 2)), 'UTC') AS observation_period_end_datetime,
  period_type_concept_id
 FROM omop_cdm.observation_period;
 
diff --git a/Oracle/OMOP CDM ddl - Oracle.sql b/Oracle/OMOP CDM ddl - Oracle.sql
index 76011cc7..7842b8ee 100644
--- a/Oracle/OMOP CDM ddl - Oracle.sql	
+++ b/Oracle/OMOP CDM ddl - Oracle.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		TIMESTAMP WITH TIME ZONE		NOT NULL ,
      observation_period_end_date		DATE		NOT NULL ,
-     observation_period_end_datetime		TIMESTAMP WITH TIME ZONE		NOT NULL ,
 	 period_type_concept_id				INTEGER		NOT NULL
     ) 
 ;
diff --git a/PostgreSQL/OMOP CDM ddl - PostgreSQL.sql b/PostgreSQL/OMOP CDM ddl - PostgreSQL.sql
index acc06c6c..bc477def 100644
--- a/PostgreSQL/OMOP CDM ddl - PostgreSQL.sql	
+++ b/PostgreSQL/OMOP CDM ddl - PostgreSQL.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		TIMESTAMP		NOT NULL ,
      observation_period_end_date		DATE		NOT NULL ,
-     observation_period_end_datetime		TIMESTAMP		NOT NULL ,
 	 period_type_concept_id				INTEGER		NOT NULL
     ) 
 ;
diff --git a/Redshift/OMOP CDM ddl - Redshift.sql b/Redshift/OMOP CDM ddl - Redshift.sql
index 7af70af1..f190be19 100644
--- a/Redshift/OMOP CDM ddl - Redshift.sql	
+++ b/Redshift/OMOP CDM ddl - Redshift.sql	
@@ -248,9 +248,7 @@ 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		timestamp	not null ,
   observation_period_end_date			date		not null ,
-  observation_period_end_datetime		timestamp	not null ,
   period_type_concept_id				integer		not null
 )
 distkey(person_id)
diff --git a/Sql Server/OMOP CDM ddl - SQL Server.sql b/Sql Server/OMOP CDM ddl - SQL Server.sql
index 7a45afc5..e76e22ae 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
 )
 ;