How do rats give birth? - briefly
Female rats have a gestation of roughly 21–23 days and give birth to a litter of pups through a brief vaginal delivery, after which the mother immediately licks each newborn to stimulate breathing and clean them.
How do rats give birth? - in detail
Rats reproduce with a rapid reproductive cycle. After successful copulation, the female enters a gestation period of approximately 21‑23 days. During this time, embryos develop in the uterine horns, each receiving nourishment through a placenta that supplies oxygen and nutrients while removing waste.
Parturition proceeds in three distinct phases:
- First stage (dilation): The cervix softens and expands under the influence of oxytocin and prostaglandins. Contractions begin at low frequency, preparing the birth canal.
- Second stage (expulsion): Strong, rhythmic uterine contractions force each pup through the birth canal. Pups are born tail‑first, a position that minimizes the risk of injury. The average litter contains 6‑12 offspring, though numbers can vary with species and environmental conditions.
- Third stage (placental expulsion): After the last pup is delivered, uterine activity continues to detach and expel the placental membranes. The mother typically consumes the placentas, reclaiming nutrients and reducing scent that could attract predators.
Immediately after birth, each newborn exhibits a pink, hairless body, closed eyes, and limited mobility. The mother licks each pup to stimulate respiration, clear amniotic fluid, and promote circulation. She then arranges the litter in a nest she has built from shredded material, providing warmth and protection.
Milk production begins within a few hours postpartum. The young attach to the nipples and nurse every 1‑2 hours, receiving a nutrient‑rich secretion that supports rapid growth. The mother remains vigilant, responding to distress calls with aggressive defense against potential threats.
Hormonal regulation underlies the entire process. Elevated estrogen levels trigger cervical ripening, while a surge of prolactin after delivery sustains lactation. Oxytocin, released in response to pup suckling, reinforces uterine contraction and maternal bonding.
Overall, the rat’s reproductive strategy combines a short gestation, large litter size, and intensive maternal care, enabling swift population expansion under favorable conditions.