Section 4W. A health maintenance contract issued or renewed within or without the commonwealth that covers a child under the age of 18 shall provide coverage for the cost of treating cleft lip and cleft palate for the child. The coverage shall include benefits for medical, dental, oral and facial surgery, surgical management and follow-up care by oral and plastic surgeons, orthodontic treatment and management, preventative and restorative dentistry to ensure good health and adequate dental structures for orthodontic treatment or prosthetic management therapy, speech therapy, audiology and nutrition services, if such services are prescribed by the treating physician or surgeon and such physician or surgeon certifies that such services are medically necessary and consequent to the treatment of the cleft lip, cleft palate or both. The coverage required by this section shall be subject to the terms and conditions applicable to other benefits. Payment for dental or orthodontic treatment not related to the management of the congenital conditions of cleft lip and cleft palate shall not be covered under this section.