It is possible to be pregnant and give birth with out any medical tests or interventions, so no none of them are actually necessary generally speaking. There are many that have benefits, like ultrasounds, induction medications when needed, and c-sections when needed, and we are blessed to have access to these things.
Whether or not you personally need them will depend on your pregnancy and birth. There are some tests that are required by providers and you need to know what those are. Most of the time you can refuse screenings and vaccines as well as interventions in labor as long as the baby's and/or your life are not in danger. Remember to ask about these things in the beginning so you do not end up in a situation where you feel forced or coerced into doing something you are not comfortable with or do not know what it.
We will discuss specific tests and interventions in the future so you can have a better idea of what they are and know what you are OK with in your pregnancy and delivery.