What Prenatal Tests Are Actually Required vs. Optional in California?

Birthstone Midwifery

Prenatal Care · Informed Consent

What Prenatal Tests Are Actually
Required vs. Optional in California?

By Tayna Chessman, LM, CPM  ·  Birthstone Midwifery

One of the most empowering things you can do during pregnancy is understand which prenatal tests are genuinely recommended — and which ones are optional choices that you get to make based on your own values and circumstances.

The answer that most providers do not tell you clearly enough: no prenatal test is legally required in California. Every test is offered under the principle of informed consent — meaning you have the right to accept or decline each one.

"Routine does not mean required. Every test offered during your pregnancy is a recommendation — not a mandate. You get to decide."

Common Prenatal Tests — Routine vs. Optional

Test	When	Status	Purpose
Blood type and Rh factor	First trimester	Routine	Identifies Rh incompatibility risk
CBC (complete blood count)	First trimester	Routine	Checks for anemia and platelet levels
Rubella immunity	First trimester	Routine	Confirms immunity to rubella
STI screening	First trimester	Routine	Screens for infections affecting pregnancy
First trimester screening	11–14 weeks	Optional	Screens for chromosomal conditions
Cell-free DNA (NIPT)	10+ weeks	Optional	Screens for chromosomal conditions
Anatomy ultrasound	18–20 weeks	Routine	Assesses fetal anatomy and development
Glucose tolerance test	24–28 weeks	Routine	Screens for gestational diabetes
Group B Strep (GBS)	35–37 weeks	Routine	Screens for bacteria affecting newborn
Non-stress test (NST)	Third trimester	Optional	Monitors fetal wellbeing at 40+ weeks
Growth ultrasound	Varies	Optional	Assesses fetal size — often offered when baby measures large

A Note on Growth Ultrasounds

One of the most commonly recommended — and most misunderstood — prenatal tests is the growth ultrasound ordered when a provider suspects the baby may be large for gestational age. Third-trimester ultrasound estimates of fetal weight carry an error margin of up to 20%. A baby measuring large on ultrasound does not automatically mean your baby is too big to be born vaginally. This is a conversation worth having in depth with your provider before agreeing to additional testing or intervention.

How Birthstone Midwifery Handles Prenatal Testing

At every prenatal visit, I discuss each upcoming test before it is offered — what it is, what it looks for, what acting on the results might look like, and what declining means. You make the decision. I give you the information. That is informed consent in practice.

Frequently Asked Questions

Can I decline the glucose tolerance test?

Yes. The glucose tolerance test is offered, not required. Some families choose alternative screening methods or decline altogether. If you decline, we discuss what that means for monitoring the remainder of your pregnancy and document your informed decision.

Is the Group B Strep test required in California?

No. GBS testing is strongly recommended because GBS colonization can affect newborns, but it is not legally required. If you decline testing or are GBS positive, we have a detailed conversation about your options for labor management.

Do I have to have ultrasounds during pregnancy?

No prenatal ultrasound is legally required. The anatomy ultrasound at 18–20 weeks is routinely recommended because it provides important information about fetal development. Whether to have any ultrasound is ultimately your decision made with full information.

What if I want more information about a specific test before deciding?

A virtual midwifery consulting session with Birthstone Midwifery is a perfect space to go deep on any specific prenatal test — what it is, what the research says, and what you would do with the information. Book a session here →

Want to Talk Through Your Prenatal Test Options?

A virtual midwifery session with Tayna Chessman, LM, CPM is exactly the space for this conversation — unhurried, thorough, and completely personalized to your pregnancy and your values.

Book a Virtual Session →

Tayna Chessman, LM, CPM (#784) is a California Licensed Midwife and the founder of Birthstone Midwifery,
serving families in Temecula, Murrieta, Winchester, Menifee, Lake Elsinore, and throughout Riverside County, California.