How long do mouse births last? - briefly
Mouse gestation lasts approximately 19–21 days from conception to delivery. Litters are typically born within this three‑week period.
How long do mouse births last? - in detail
Mice complete gestation in approximately 19–21 days, after which the actual birthing event begins. The active labor phase typically lasts from 30 minutes to 2 hours, depending on litter size and maternal condition.
During the first stage, the uterus contracts to position the embryos; this period is brief, often under 10 minutes, and may be indistinguishable from normal activity. The second stage, when pups are expelled, proceeds in rapid succession. A single newborn is delivered every 2–5 minutes, with intervals lengthening slightly as the litter progresses. For a typical litter of 6–8 pups, the entire delivery sequence finishes within 15–30 minutes.
The third stage involves expulsion of the placental membranes. Each placenta is usually expelled immediately after its corresponding pup, taking about 1 minute per placenta. The mother frequently consumes the membranes, a behavior that reduces predation risk and promotes uterine involution.
Factors that can extend the birthing period include:
- Large litters (>10 pups) – increased number of expulsions lengthens the overall process.
- Maternal age or health issues – weakened uterine tone may slow contractions.
- Environmental stressors – temperature extremes or disturbances can delay labor onset.
In laboratory strains such as C57BL/6, the timeline aligns closely with the ranges above, while wild‑derived mice may exhibit slightly longer durations due to variable litter sizes and environmental conditions.
Post‑delivery, pups are usually born hairless and blind, gaining fur and opening their eyes within 10–14 days. The mother initiates nursing within minutes, ensuring rapid thermoregulation and nourishment.