When do mice give birth? - briefly
Mice give birth after a gestation of roughly 19–21 days, producing litters throughout the year with a seasonal peak in spring.
When do mice give birth? - in detail
Mice reach sexual maturity between five and eight weeks of age, after which females become capable of conceiving. The reproductive cycle is rapid: estrus lasts 4–5 hours, and ovulation occurs shortly after mating. Gestation spans 19–21 days, with most deliveries occurring on day 20. Litters typically contain 5–8 pups, though numbers can vary from 3 to 12 depending on strain and nutrition.
Key factors influencing parturition timing:
- Photoperiod: longer daylight accelerates onset of breeding season.
- Temperature: ambient warmth (22–26 °C) supports optimal gestation.
- Nutrition: protein‑rich diets increase litter size and reduce gestation length marginally.
- Social environment: presence of a dominant male can suppress estrus in subordinate females.
Mice can produce multiple litters annually. After weaning (around 21 days), a female may become pregnant again within 24 hours, allowing up to 5–6 litters per year under laboratory conditions. In wild populations, seasonal constraints limit breeding to spring and summer, aligning births with peak food availability.