Interrupted labour is common enough in queens, especially primagravida and domestic breeds, as to be a normal occurrence.
The interruption, which may last as long as 24 or even 36 hours, may be triggered by a disturbance or may be attributable to no changes at all.
After one or more kittens have been born, the queen will stop contracting and rest, suckling the kittens already born. She will remain bright and often take food and water.
After this period of rest the queen will recommence contractions and the remainder of the litter should be born normally and easily.