Males only mate if a female goes into heat(every 4 days) Some frisky boys may try to breed slightly earlier. They generally won't breed if the female isn't in heat or sexually receptive.
If a female becomes pregnant, the males won't breed until the litter is born. Once a female drops a litter, she goes into heat for a few hours after birth. If she isn't bred within that time window, she cannot breed or become pregnant again until the litter is weaned.
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