doctrine2 with php Datetime month

I have some events stored in a database using doctrine and Symfony2, and those events have a two datetime parameters, start and end of the event. I need to know if those events are active during a certain month, but i cant find a way. I tried with :

$now = new \Datetime('now');
    $qb  = $this->createQueryBuilder('e');

    $qb->where('e.start <= :now AND e.end >= :now')
       ->setParameter('now', $now);

    return $qb->getQuery()
              ->getArrayResult();

but it limits to the day, and not to the month. Is there a way to check it ? Thanks a lot !

You can use the following code

$monthStart = new DateTime(date('Y-m-01') . " 00:00:00");
$monthEnd = new DateTime(date('Y-m-t'). " 23:59:59");

$qb  = $this->createQueryBuilder('e');

$qb
   ->where('e.start <= :end AND e.end >= :start')
   ->setParameter('start', $monthStart)
   ->setParameter('end', $monthEnd);

return $qb->getQuery()
          ->getArrayResult();