What Animal Has the Longest Pregnancy?
Credit: Los Angeles Zoo

Elephants have the longest gestation period of all mammals. These gentle giants' pregnancies last for more than a year and a half.

The average gestation period of an elephant is about 640 to 660 days, or roughly 95 weeks. By comparison, a human pregnancy lasts an average of 280 days, or 40 weeks. Female elephants live for 60 to 70 years, but only have about four offspring throughout their lifetime.

Although elephants usually only carry one baby at a time, one to two percent of elephant births produce twins. When an elephant gives birth, the other elephants in the herd form a protective circle around the mother during the delivery .

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