* Infanticide: Male mice often kill their own offspring, especially if they are not the father of the litter. This behavior is driven by a combination of factors, including hormones, competition for resources, and the need to ensure their own genes are passed on.
* Stress for the Mother: The presence of the male can be stressful for the mother, which can negatively impact her ability to care for her pups.
* Aggression: Male and female mice can become aggressive towards each other, especially during breeding season, which could lead to injury or death.
It's important to separate the male from the female after she is pregnant to ensure the safety of both the mother and the pups.