How long is the gestation period for a bottlenose dolphin?

Bottlenose dolphins start the gestation period with the copulation of a pair of dolphins. After the 12 months of the gestation period, a single calf is born, usually with the help of another dolphin which assumes the role of a midwife. Dolphin mothers give birth to the calf by releasing the tail of the baby first. This is done this way, to avoid that the new dolphin gets drown. The calf is nursed for up to 18 months with milk produced by the mother.After that, young dolphins stay with their mothers for around 6 years until they have developed all the skills for hunting and surviving.