When does a rat give birth to pups? - briefly
Rats usually deliver their litters after a gestation period of approximately 21–23 days, resulting in several offspring per birth.
When does a rat give birth to pups? - in detail
Rats reach parturition after a gestation of approximately 21 – 23 days, with 22 days representing the mean for the common laboratory species. Strain differences, ambient temperature, and nutritional status can shift the interval by one to two days in either direction.
The reproductive cycle proceeds as follows: estrus lasts 12–14 hours, after which mating typically occurs within the next 24 hours. Fertilization takes place in the oviduct, and implantation of embryos is completed by day 5–6 post‑coitus. Placental development and fetal organogenesis dominate days 7–14, while rapid fetal growth and positioning for delivery occur between days 15 and 21.
Key physiological markers of imminent delivery include:
- Enlargement of mammary glands and secretion of colostrum
- Construction of a nest using bedding material
- Reduced activity and increased nesting behavior
- Swelling of the abdomen and visible uterine contractions
The actual birth process lasts roughly 30–60 minutes for a typical litter of six to twelve pups. Each offspring is expelled sequentially, with intervals of 2–5 minutes between individuals. The mother typically licks each pup to stimulate respiration and to clear the birth canal.
After birth, neonates are altricial: they remain blind, hairless, and dependent on maternal care for the first three weeks. The mother provides warmth, nutrition, and protection until the pups achieve weaning at approximately 21 days of age.