(a) A permanent employee, or an employee holding a position by permanent or temporary appointment who requests leave because of pregnancy or childbirth, may, in the discretion of the appointing authority, be granted a leave of absence, without pay, for a period not exceeding two years. Such leave may be extended beyond two years, for periods aggregating not in excess of an additional two years, only with the approval of the Civil Service Commission. In an exceptional case, a further extension may be permitted by the commission for good cause shown and where the interests of the government would be served. For the purposes of this Part, time spent in active service in the military forces of the United States or of the State of New York shall not be considered in computing the period of leave.

(b) This section shall not be construed to require the extension of any employment beyond the time at which it would otherwise terminate by operation of law, rule or regulation.