Among humans, the period of time between conception and birth is called pregnancy. What is this period of time called among other mammals?

While humans typically refer to the nine-month period of carrying a child as pregnancy, the broader scientific term used for all mammals is gestation. This word derives from the Latin "gestare," meaning "to carry" or "to bear," and it describes the entire timeline of development for an embryo and fetus within the mother's uterus, from fertilization until birth. Although "pregnancy" is perfectly correct for humans, gestation is the more universal term that applies across the entire class of mammals.

The length of the gestation period is incredibly diverse and highlights the vast range of mammalian life strategies. It can be as short as 12 days for the Virginia opossum, whose tiny, underdeveloped young must then crawl to a pouch to complete their growth. This short internal development followed by external pouch-life is a hallmark of marsupials and stands in stark contrast to placental mammals.

At the other extreme, the African elephant holds the record for the longest gestation period of any land animal, lasting an astonishing 22 months. This extended time is necessary for the complex development of the elephant's massive body and highly advanced brain, ensuring the calf is relatively mature and capable of walking shortly after birth. Factors like adult body size, litter size, and the developmental state of the newborn all influence the length of this critical period.