What Animals have the Shortest Gestation Period?

The duration of gestation period can be influenced by various factors, including size and complexity of the offspring, temperature, humidity and nutrition of the environment, hormones and genetics.

In another post we listed animals with the longest gestation periods and this time we are going to take a look to the other end of the spectrum.

Here are some animals with the shortest gestation period:

Rabbit (28-31 days)

Unlike some other animals, rabbits are induced ovulators, which means that ovulation is triggered by sexual activity, rather than occurring on a regular cycle. Rabbits are known for their reproductive prowess, and under ideal conditions, a single female can produce up to 8 litters per year.

Rabbits are popular as pets and as a source of meat and fur in many parts of the world. They are also used extensively in scientific research, due to their relatively large size and physiological similarities to humans.

In comparison, after 28-31 days a human embryo has formed fingers and toes and is beginning the ossification (hardening) of bones

Mouse (19-21 days)

After a brief gestation period of 19-21 days, the female mouse gives birth to a litter of young, which are born relatively underdeveloped but with fur and their eyes and ears open.

House mice are prolific breeders, and under ideal conditions, a single female can produce up to 10 litters per year. The average litter size for house mice is around 6-8.

For the human embryo, days 19-21 mark the beginning of development of the brain and spinal cord, formation of the first blood cells and blood vessels and formation of the pharyngeal arches (which will later become the face, jaw and neck structures).

Mole (18-19 days)

Moles, especially American shrew moles (aka eastern mole) have on average a gestation period of just 18-19 days. Shrew moles are placental mammals, which means that the embryo receives nourishment and oxygen from the mother via the placenta.

After the brief gestation period, the shrew mole gives birth to a litter of young, which are born relatively underdeveloped but fully furred and with their eyes and ears open.

After 18-19 days of development, a human embryo is beginning the development of eyes and ears and the formation of limb buds is finished.

Antechinus (15-16 days)

The brown antechinus is a small marsupial that is found in Australia. Like other marsupials, the female brown antechinus gives birth after just 15-16 days of gestation to relatively underdeveloped young, which then continue to develop outside of the mother’s body in a pouch.

It’s worth noting that the brown antechinus has a unique reproductive strategy, in which the males die shortly after mating. This is because the intense mating season places a significant strain on their bodies, leading to a condition known as male antechinus syndrome, in which their immune systems are overwhelmed and they eventually succumb to stress and exhaustion.

In comparison, after 15-16 days of development human embryo has completed the formation of placenta and primitive streak. This also marks the start of heart formation and heartbeat.

Opossum (12-15 days)

Opossums are marsupials, a group of mammals that typically have longer gestation periods than placental mammals. Therefore it is quite remarkable that opossums have one of the shortest gestation periods of any mammal.

After the brief gestation period of just 12-15 days, the tiny and underdeveloped joeys are born and must make their way to the mother’s pouch, where they attach themselves to a nipple and continue to develop for 2-3 months.

In comparison, a 12-15 days old human embryo has implanted into the lining of uterus and is going through rapid cell division and differentiation.