Fertility Blood Tests Explained: AMH, FSH, and What to Expect

Your First Fertility Lab Tests at STL Fertility in St. Louis

After your first consultation at STL Fertility, one of the first steps in your fertility evaluation is fertility blood testing.

You may hear our team use several different terms for this — labs, labwork, bloodwork, or diagnostic labs — but they all mean the same thing: a set of blood tests that help our STL Fertility physicians understand your reproductive health and guide the next steps in your care.

These tests give your physician important information about your hormones, ovarian reserve, and overall health, allowing us to create a personalized fertility plan tailored to you.

If you are new to fertility care, this guide will walk you through what these blood tests measure, why they matter, and what to expect during your visit.

Why Fertility Testing Starts with Bloodwork

Your first fertility labs provide a snapshot of your reproductive hormone health.

These tests help evaluate:

• Ovarian reserve (the remaining egg supply)

• Hormone balance needed for ovulation

• Medical conditions that could impact fertility

Fertility involves communication between multiple systems in the body — including the brain, ovaries, thyroid gland, and reproductive hormones. Blood testing allows physicians to see how these systems are working together.

Every patient’s testing plan is personalized, but most patients will complete several core fertility hormone tests during their initial evaluation.

Key Fertility Blood Tests We Check

AMH Test (Anti-Müllerian Hormone)

The AMH test is one of the most important fertility blood tests because it helps estimate ovarian reserve, or the number of eggs remaining in your ovaries. AMH is produced by small follicles in the ovaries that contain immature eggs.

Our STL Fertility physicians use AMH levels to understand:

• Egg supply

• Ovarian function

• How the ovaries may respond to fertility medications

General interpretation:

• Higher AMH → suggests a larger egg supply

• Lower AMH → suggests a smaller egg supply (which naturally declines with age)

It is important to know that AMH does not predict whether you can get pregnant naturally. Instead, it helps physicians plan the most appropriate fertility treatment if needed.

Cycle Day 3 Fertility Testing: FSH and Estradiol

Another important part of fertility testing is measuring FSH and Estradiol, often referred to as Cycle Day 3 labs. These hormones are typically measured on day 3 of your menstrual cycle (the first day of bleeding is considered cycle day 1). These tests evaluate how the brain and ovaries communicate.

FSH (Follicle Stimulating Hormone) Produced by the pituitary gland in the brain, FSH signals the ovaries to grow follicles each month.

Estradiol (E2) Estradiol is produced by developing ovarian follicles as eggs mature.

Together, these hormones help physicians evaluate how well the ovaries respond to hormonal signals early in the menstrual cycle.

Thyroid Testing and Fertility (TSH, T3, T4)

Your thyroid gland plays a key role in fertility and early pregnancy.

Thyroid hormones influence:

• Ovulation

• Menstrual cycle regularity

• Implantation and early pregnancy

Even mild thyroid imbalances can affect fertility. Checking TSH, T3, and T4 levels helps ensure hormones are optimized before pregnancy.

Prolactin and Additional Hormone Testing

Your physician may also check prolactin, a hormone that normally increases after childbirth to support breastfeeding. When prolactin levels are elevated outside pregnancy, it can sometimes interfere with ovulation. Additional hormones such as LH or androgen levels may also be tested depending on your symptoms or medical history.

General Health and Infectious Disease Screening

Fertility bloodwork also includes tests that evaluate overall health and safety before treatment. These may include:

• CBC (Complete Blood Count)

• CMP (Comprehensive Metabolic Panel)

• Routine infectious disease screening

These tests are important before treatments like IUI (intrauterine insemination) or IVF (in vitro fertilization).

Genetic Carrier Screening

Many patients also choose to complete genetic carrier screening, which is a blood test that checks whether you carry genes for certain inherited conditions. Common conditions screened include:

• Cystic fibrosis

• Spinal muscular atrophy

• Other inherited genetic disorders

Most people who are carriers are healthy and have no symptoms. The purpose of carrier screening is to see whether both partners carry the same gene, which could increase the chance of passing a condition to a child.

If both partners are carriers, your physician can discuss reproductive options that reduce that risk.

What Happens During Your Fertility Lab Appointment

Your fertility bloodwork is typically completed right in our STL Fertility office.

One of our experienced team members will draw a small blood sample from your arm. The entire process usually takes less than 10 minutes.

Once results return, your physician carefully reviews each marker and our team explains what the results mean for your fertility journey. These results allow us to design a personalized fertility treatment plan tailored to your goals.

How Fertility Lab Results Guide Your Treatment Plan

Your initial lab results provide the foundation for your fertility care plan.

Depending on the results, your physician may recommend:

• Ovulation monitoring

• Fertility medications

• IUI (intrauterine insemination)

• IVF (in vitro fertilization)

• Additional diagnostic testing such as an HSG (hysterosalpingogram)

Every treatment plan is individualized based on your medical history, lab results, and family-building goals.

Fertility Blood Testing in St. Louis

Patients across St. Louis, Clayton, Ladue, Chesterfield, and the greater Missouri and Illinois region come to STL Fertility for comprehensive fertility evaluation.

Our physician-led team offers advanced fertility diagnostics including:

• AMH ovarian reserve testing

• Day 3 fertility hormone testing (FSH and estradiol)

• Thyroid hormone testing

• Genetic carrier screening

• Ultrasound fertility evaluation

All testing can be completed conveniently onsite at STL Fertility, allowing patients to move quickly from evaluation to treatment if needed.

If you are searching for fertility testing in St. Louis, our team is here to guide you every step of the way.

Considering Fertility Testing?

Understanding your fertility hormones is often the first step toward building your family.

The physician team at STL Fertility provides comprehensive fertility testing and personalized care plans for patients across the St. Louis region.

Schedule your consultation today to get started.

Common Questions About Fertility Blood Tests

What fertility blood tests are done first?

Initial fertility testing usually includes AMH, FSH, estradiol, thyroid testing, and prolactin, along with general health screening. These tests help physicians evaluate ovarian reserve, hormone balance, and overall reproductive health.

What does the AMH test tell you?

The AMH test measures ovarian reserve, or the number of eggs remaining in the ovaries.

It helps doctors estimate how the ovaries may respond to fertility treatments.

Do fertility blood tests require fasting?

Most fertility hormone tests do not require fasting, although your care team will let you know if any preparation is needed.

How long does fertility blood testing take?

The blood draw itself usually takes less than 10 minutes, and most results return within a few days to one week.

Start Your Fertility Evaluation with STL Fertility

Beginning fertility testing can feel like a big step — but it is also an empowering one.

At STL Fertility, our physician-led team combines advanced reproductive science with compassionate care to help you understand your fertility and plan your next steps with confidence.

If you are ready to begin fertility testing in St. Louis, we are here to help.

Schedule your consultation with STL Fertility today.