“What are the disadvantages of having a doula?”

If you have already decided to hire a doula, I suppose you have evaluated the advantages and the benefits of hiring one; I do not know of any disadvantages. There are a couple of experts that provide parental support to expectant and new parents. Doulas are a great fit if you want help with delivery and breathing techniques; if you wish to have help navigating postpartum effortlessly, other experts can help with that. You will need to weigh the opportunities and costs of going with any expert you want to hire. I hope this helps you make an informed decision.