As mammals, dolphin young are born live from their mothers’ wombs. Only one baby is born at a time and they come out tail-first.  

 

As soon as the baby dolphin is born, she needs to get a lung full of breath to avoid drowning; so her mother will often nudge her to the surface to take her first gulp of air.

 

Baby dolphins suckle milk from their mother in order to feed and grow. Later on, their mother will introduce them to solid food.

 

Young dolphins may stay with their mothers and the mother's group until they are some six or seven years old. Then the young dolphins will be old enough to become independent.

 

Young dolphins need to stay with their mothers (or their mothers' group) for this long  not only because they are not strong enough to stay safe from predators like sharks, but because they have a good deal to learn about other dolphins, hunting fish, and general living.

 

Dolphin communications can be complicated and it takes a long time to learn about how to interact with other dolphins.

 

 

After young male dolphins seperate from their mothers, they will often stay in groups with other youngsters. Young female dolphins are more likely to stay with their mothers for longer in a 'matrilineal' group.

 

Source: Sarasotadolphin.org