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This is a collection of lists of mammal gestation period estimated by experts in their fields. The mammals included are only viviparous (marsupials and placentals) as some mammals, which are monotremes (including platypuses and echidnas) lay their eggs. A marsupial has a short gestation period, typically shorter than placental.
Gestational age: 3 weeks and 0 days until 3 weeks and 6 days old. 22–28 days from last menstruation. Embryonic age: Week nr 2. 1 week old. 8–14 days from fertilization.
For different species, the timing of the rut depends on the length of the gestation period , usually occurring so the young are born in the spring. This is shortly after new green growth has appeared thereby providing food for the females, allowing them to provide milk for the young, and when the temperatures are warm enough to reduce the risk ...
In the case of whales, dolphins and porpoises, the single calf is normally born tail first which minimizes the risk of drowning. [7] The mother encourages the newborn calf to rise to the surface of the water to breathe. [8] Large mammals which give birth to twins is much more rare, but it does occur occasionally even for mammals as large as ...
Gestation, called pregnancy in humans, is the period of time during which the fetus develops, dividing via mitosis inside the female. During this time, the fetus receives all of its nutrition and oxygenated blood from the female, filtered through the placenta , which is attached to the fetus' abdomen via an umbilical cord .
The normal period of gestation (pregnancy) is about nine months or 36 weeks. The germinal stage refers to the time from fertilization through the development of the early embryo until implantation is completed in the uterus. The germinal stage takes around 10 days. [1] During this stage, the zygote divides in a process called cleavage.
In mammals, pregnancy is the period of reproduction during which a female carries one or more live offspring from implantation in the uterus through gestation. It begins when a fertilized zygote implants in the female's uterus , and ends once it leaves the uterus.
Gestational age at birth is on average shortened by various pregnancy aspects: twin pregnancy, prelabor rupture of (fetal) membranes, pre-eclampsia, eclampsia, intrauterine growth restriction. [29] The ratio between fetal growth rate and uterine size (reflecting uterine distension) is suspected to partially determine the pregnancy length. [30]