Overview of Reproductive Process As mice breed throughout the year, a single female produces between five and 10 litters annually. Each brood can contain up to 12 young, but the average litter size hovers around five or six babies. Young mice grow quickly and usually only need three weeks before they're fully weaned from their mothers. The pests achieve sexual maturity after five to seven weeks. Quick Reproduction Leads to Large Infestations Once infestations of mice are established in homes, they reproduce quite rapidly. As populations grow, more food is contaminated and residents are put at higher risk of contracting diseases. To eliminate infestations before mice numbers get out of hand, homeowners should contact trained pest professionals at the first sign of mouse activity. Critter Control specialists eliminate the pests and provide helpful tips for avoiding future infestations.