The gestation period is about 12 months.

Worldwide, calves are born throughout the year.

Seasonal calving peaks vary by area.

A female dolphin can potentially bear a calf every two years, but calving intervals generally average three years.

Calves are born in the water. Deliveries are usually tail-first, but head-first deliveries are also seen. The umbilical cord snaps during delivery.

Sometimes an assisting dolphin may stay close to the new mother and calf. Although this assisting dolphin often is referred to as an "auntie" dolphin, it may be male or female. This auntie dolphin is often the only other dolphin a mother allows near her calf.

Calves are approximately 100 to 135 cm (39–53 in.) long and weigh about 10 to 20 kg (22–44 lb.).

In the first few days after birth, the calf’s dorsal fin and tail flukes are pliable and lack firmness, but gradually stiffen.

Calves, darker than adults, show several vertical, light lines on their sides, a result of fetal folding. These lines disappear within six months.

Nursing.

In caring for her calf, a mother dolphin stays close by and attentively directs the calf's movements. The calf is carried in the mother's "slip stream," the hydrodynamic wake that develops as the mother swims. This helps the baby swim and enables the mother and calf to stay up with the group.

There is probably a considerable amount of learning involved in mothering.

Bottlenose dolphin breeding colonies in marine zoological parks continue to provide a unique opportunity to observe and quantify dolphin reproductive biology.

In zoological environments, calves begin to take a few fish at about three to four months, when their teeth begin to erupt. Calves begin to eat fish when they reach about 130 to 150 cm (51–59 in.).

Within a few days of birth a calf can vocalize, but signature characteristics develop with age.