1. Fertilization:
* Sperm fertilizes an egg inside the female's body. This happens in the fallopian tubes for most mammals.
2. Gestation:
* The fertilized egg implants in the uterus, where it develops within a placenta.
* The placenta connects the developing embryo to the mother's bloodstream, providing oxygen and nutrients while removing waste.
* The length of gestation varies greatly depending on the species, ranging from a few weeks (like mice) to over a year (like elephants).
3. Labor and Delivery:
* Hormonal changes trigger labor, which includes contractions of the uterus and dilation of the cervix.
* The fetus is pushed out of the birth canal, often aided by the mother's muscles.
* The umbilical cord is cut, severing the connection to the placenta.
4. Postpartum:
* The mother typically cleans and cares for her newborn.
* Many mammals, especially those with young that are born relatively helpless, nurse their offspring with milk produced by mammary glands.
Here are some additional points about mammalian birth:
* Placental mammals: The majority of mammals are placental mammals, meaning they have a placenta that allows for nutrient and waste exchange between the mother and developing fetus.
* Marsupials: Marsupials (like kangaroos and koalas) give birth to relatively undeveloped young that complete their development in a pouch on the mother's abdomen.
* Monotremes: Monotremes (like the platypus and echidnas) are unique mammals that lay eggs. However, they still nurse their young after they hatch.
Let me know if you have more questions!