How does a house mouse give birth? - briefly
A female house mouse carries a gestation of about 19‑21 days and then delivers a litter of 5‑12 altricial pups through a brief vaginal birth; the newborns are blind, hairless, and dependent on the mother for warmth and nutrition. Shortly after delivery, the mother cleans the pups, initiates nursing, and begins the rapid cycle of growth that leads to sexual maturity within six weeks.
How does a house mouse give birth? - in detail
The domestic mouse reproduces rapidly, with a cycle that progresses from mating to the delivery of a litter within a few weeks.
Mating occurs when a female in estrus accepts a male. The estrous phase lasts 4–5 days, during which the female’s vaginal opening swells and a scent cue signals receptivity. Copulation is brief; the male mounts, deposits a sperm‑rich ejaculate, and withdraws after a few seconds. Sperm travel through the female reproductive tract, reaching the oviducts where fertilization takes place.
Following fertilization, the zygote undergoes cleavage as it moves toward the uterus. Implantation occurs around day 4 of gestation. The embryo develops within a placenta that supplies nutrients and oxygen. The gestation period for a house mouse averages 19–21 days, during which the embryos progress through the following stages:
- Days 5‑7: Blastocyst formation and early organogenesis.
- Days 8‑12: Rapid growth of somites, limb buds, and neural tube.
- Days 13‑16: Development of sensory organs, fur, and skeletal calcification.
- Days 17‑19: Final maturation of lungs and preparation for birth.
Parturition begins with a series of coordinated uterine contractions. The female adopts a curled, protective posture, often nesting in a secluded area with soft bedding. Each pup is expelled individually, typically within a few seconds of one another. A typical litter contains 5–8 offspring, though numbers can range from 3 to 12.
Immediately after birth, the mother cleans each newborn with her mouth, stimulates respiration, and initiates nursing. The pups are altricial: they lack fur, have closed eyes, and are completely dependent on maternal care. Milk production starts within 12 hours, providing essential antibodies and nutrients. The mother remains with the litter for approximately three weeks, during which the young gain weight rapidly, open their eyes around day 14, and are weaned by day 21.
Throughout the reproductive cycle, hormonal regulation—principally estrogen, progesterone, and prolactin—governs ovulation, implantation, uterine readiness, and lactation. This tightly controlled sequence enables the house mouse to produce multiple litters each year, contributing to its high population growth potential.