Solely for purposes of determining whether a break in service for participation and vesting purposes has occurred in a computation period, an individual who is absent from work for maternity or paternity reasons shall receive credit for the hours of service that would otherwise have been credited to such individual but for such absence, or in any case in which such hours cannot be determined, 8 hours of service per day of such absence. For purposes of this paragraph, an absence from work for maternity or paternity reasons means an absence # by reason of the pregnancy of the individual, # by reason of a birth of a child of the individual, # by reason of the placement of a child with the individual in connection with the adoption of such child by such individual, or # for purposes of caring for such child for a period beginning immediately following such birth or placement. The hours of service credited under this paragraph shall be credited: # in the computation period in which the absence begins if the crediting is necessary to prevent a break in service in that period, or # in all other cases, in the following computation period. No more than 501 hours of service shall be credited under this paragraph for any single continuous period (whether or not such period occurs in a single computation period).