<prompt> Most common cause of cervical insufficiency isIdiopathicPrevious dilatationExposure to DESConization  <response>: The most common cause of cervical insufficiency is idiopathicCervical incompetence may be congenital due to the following:Mullerian anomaliesCollagen disordersExposure to DES or the causes may be acquiredObstetric trauma like cervical laceration during deliveryMechanical dilatationCervical Conization 