How long does a rat's birth take? - briefly
The gestation period for a rat lasts approximately 21‑23 days, and the actual delivery of a litter typically completes within 15‑30 minutes.
How long does a rat's birth take? - in detail
Rats complete gestation in approximately 21–23 days. Parturition proceeds through three distinct stages, each with a characteristic duration.
- Stage I – Preparatory phase: Hormonal changes trigger nest construction, vulvar swelling, and abdominal contractions. This phase lasts roughly 12–24 hours before the first pup is expelled.
- Stage II – Expulsion of offspring: Individual pups are delivered at intervals of 15–30 minutes. The entire expulsion period generally spans 1–2 hours, during which the dam exhibits rhythmic abdominal contractions and may turn the pups to assist breathing.
- Stage III – Placental removal: After the last pup, the placentae are expelled. This final phase requires 10–30 minutes and is followed by maternal grooming of the litter.
Key physiological markers accompany each phase. Oxytocin peaks during Stage II, driving uterine contractility. Prostaglandin release supports cervical dilation. Pup viability is enhanced by the dam’s immediate cleaning and nursing behavior, which begins within minutes after each birth.
Overall, the active labor process from the first contraction to the removal of the final placenta typically occupies 1½–3 hours, while the preparatory period extends the total birthing interval to roughly 13–27 hours.