Gestation - Mammals

Mammals

In mammals, pregnancy begins when a fertilized zygote implants in the female's uterus and ends once the fetus leaves the uterus.

Below are average and approximate values ordered by gestation period (note for humans gestational age is counted from the LMP, for other animals the counting method varies, so these figures could be 14 days off):

Animal Average gestation period (days)
American opossum 12 - 13
Golden hamster 15 - 17
House mice 18 - 20
Rabbits 33
Foxes 51 - 63
Cats 62
Dogs 65
Coatis 76-78
Leopards 94
Lions 108
Pigs 115
Beavers 122
Sheep 145
Baboons 187
Moose 245
Humans 259–294
Cattle 283
Horses 336
Tapirs 380-400
Giraffes 420-450
Sperm whales 480–590
Rhinos 487
Elephants 600–660

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