50% chance of an empty litter (1-50 is a successful breeding)

No chance of empty litter if bred to Recognized+ (50% fail with a citizen)

No chance of empty litter if bred to Recognized+ (25% fail with a citizen: 1-75 is a successful breeding)

No chance of empty litter if bred to recognized+ (10% fail with a citizen: 1-90 is a successful breeding)