PHP PDO getting multiple results / SQL Server

include ("../conexion/pod_connection.php");

$periodR=$_POST["periodR"];
$periodR = "JAN2018";
$t = 1;
$n = "";

$sth = $pdo_object->prepare("exec [dbo].[OM_simplifiedReport] @type = ?, @orgUnitName = '',
    @country = ?,
    @period = ?,
    @employmentStatus = ?  ");


 $sth->bindParam(1, $t, PDO::PARAM_INT);
 $sth->bindParam(2, $n, PDO::PARAM_STR );
 $sth->bindParam(3, $n, PDO::PARAM_STR );
 $sth->bindParam(4, $periodR, PDO::PARAM_STR );
 $sth->bindParam(5, $n, PDO::PARAM_STR );


 $sth->execute();

  $result2 = $sth->fetchAll(PDO::FETCH_OBJ);       
echo json_encode($result2);

do {
   $rows = $sth->fetchAll(PDO::FETCH_NUM);
   if ($rows) {
       echo "a : " . json_encode($rows) . "\r\n";

   }

 
} while ($sth->nextRowset());