Doulas aren't generally required to have an official certification, but this varies from state to state.
A few states have proposed policies that allow Medicaid reimbursement for doula clinics. In that case, accreditation requirements and regulations are going to increase.
Most doulas typically continue to complete extensive medical training and schooling and are encouraged to take advantage of opportunities to continue education.
Doulas often come together in community groups or doula networks to share ideas, support one another and take further courses.