If you’re thinking about having a baby, preparing for pregnancy can start long before you see a positive pregnancy test.

Preconception care isn’t about trying to make every lab value “perfect.” It’s about identifying nutritional deficiencies, metabolic dysfunction, hormonal imbalances and other potentially modifiable factors before pregnancy places additional demands on the body.

And this conversation shouldn’t only focus on women. Male factors contribute substantially to infertility, which is why fertility guidelines recommend evaluating both partners when a couple is having difficulty conceiving.

I like to think about preconception testing in two layers: foundational labs that give us a picture of overall and reproductive health, followed by functional or specialty testing when someone’s symptoms or history give us a reason to dig deeper.

Not everyone needs every test below. Testing should always be individualized based on medical history, symptoms, medications, diet, menstrual cycles and fertility history.

Foundational Labs for Women

Complete Blood Count (CBC)

A CBC evaluates red and white blood cells, hemoglobin, hematocrit and platelets.

Before pregnancy, I’m particularly interested in identifying anemia or other abnormalities that may warrant further investigation.

Iron Studies + Ferritin

Consider:

• Ferritin
• Serum iron
• TIBC or transferrin
• Transferrin saturation

Ferritin reflects stored iron. It’s possible to have hemoglobin within the laboratory reference range while iron stores are already becoming depleted.

This can be particularly important for women with heavy menstrual periods, restrictive diets, gastrointestinal conditions or a history of iron deficiency.

Vitamin B12 + Folate

Folate is especially important before conception because adequate folate around the time of conception helps reduce the risk of neural-tube defects.

Vitamin B12 is also important for DNA synthesis and neurological function and deserves particular attention in people following vegetarian or vegan diets or those with gastrointestinal conditions that may impair absorption.

Depending on the individual, I may consider:

• Vitamin B12
• Folate
• Methylmalonic acid (MMA)
• Homocysteine

MMA can provide additional information when B12 status is questionable, while homocysteine can offer another window into folate, B12 and B6-dependent metabolism.

Vitamin D

25-hydroxyvitamin D [25(OH)D] is the standard blood test used to assess vitamin D status.

Rather than automatically taking high-dose vitamin D, testing allows deficiency or insufficiency to be identified and supplementation individualized.

Thyroid Testing

At minimum, I would consider:

• TSH

Depending on symptoms, medical history and initial results, additional testing may include:

• Free T4
• TPO antibodies

Thyroid function is particularly important during conception and pregnancy, so identifying clinically significant thyroid dysfunction before pregnancy gives us an opportunity to address it early.

Metabolic Health

Consider:

• Fasting glucose
• Hemoglobin A1c

When there are risk factors for insulin resistance, PCOS or metabolic dysfunction, I may also consider:

• Fasting insulin

Fasting glucose and insulin can also be used to calculate HOMA-IR, which can sometimes reveal earlier insulin resistance that isn’t obvious from A1c alone.

Reproductive Hormones

Hormone testing should be based on the clinical question and timed appropriately within the menstrual cycle.

Depending on the situation, testing may include:

• FSH
• Estradiol
• LH
• Progesterone
• Prolactin
• Total and free testosterone
• SHBG
• DHEA-S

FSH and estradiol used for ovarian-reserve assessment are generally measured early in the menstrual cycle.

Progesterone shouldn’t automatically be checked on “day 21.” If the goal is to assess ovulation, testing should be timed to the individual’s luteal phase based on when ovulation actually occurred.

Women with regular 21–35-day cycles generally don’t need laboratory testing simply to prove that they’re ovulating.

AMH

Anti-Müllerian hormone, or AMH, can provide information about ovarian reserve, particularly the remaining quantity of eggs.

But AMH is frequently misunderstood.

It isn’t an “egg quality” test, and a low AMH doesn’t mean that someone cannot become pregnant naturally. AMH is particularly useful in fertility treatment because it can help predict ovarian response to stimulation.

For someone without infertility, AMH shouldn’t be treated as a standalone test of future fertility.

Preconception Immunity + Infectious Disease Screening

Depending on vaccination history, previous testing and individual risk, preconception testing may include:

• Rubella immunity
• Varicella immunity
• Hepatitis B/C
• HIV
• Syphilis
• Gonorrhea/chlamydia

Reviewing immunity before pregnancy is useful because certain vaccines can’t be administered during pregnancy.

Genetic Carrier Screening

Carrier screening isn’t technically a wellness lab, but it can be one of the most important components of preconception care.

Testing can identify whether someone carries genetic variants for inherited conditions that could potentially be passed to a child.

When carrier screening is completed before pregnancy, couples have more time to understand the results and discuss their reproductive options if both partners are carriers for the same recessive condition.

Foundational Labs + Testing for Men

Optimizing fertility shouldn’t mean extensively testing the woman while assuming everything is fine on the male side.

When infertility is present, both partners should be evaluated.

Semen Analysis

For a man experiencing infertility, semen analysis is foundational.

It evaluates characteristics including:

• Semen volume
• Sperm concentration
• Total sperm count
• Motility
• Morphology

Semen parameters can fluctuate, so an abnormal result may need to be repeated and interpreted in the context of the complete clinical picture.

Hormone Testing

Not every man needs an extensive reproductive hormone panel.

When semen analysis, symptoms or medical history suggest a hormonal issue, testing may include:

• Morning total testosterone
• FSH
• LH
• Prolactin

One particularly important fertility conversation involves testosterone replacement therapy. Exogenous testosterone can suppress the hormonal signaling required for sperm production and significantly impair fertility.

General + Nutritional Labs

Depending on medical history, diet and symptoms, consider:

• CBC
• CMP
• Hemoglobin A1c
• Fasting glucose
• Vitamin D
• Vitamin B12
• Folate
• Ferritin + iron studies

The goal isn’t to order every nutrient available. It’s to identify deficiencies or metabolic abnormalities that actually warrant intervention.

Functional Labs to Consider for Fertility + Preconception Optimization

This is where I take a more individualized approach.

Functional testing shouldn’t mean ordering more tests simply because we can. It should mean asking better questions and choosing tests that may help uncover a plausible contributor to someone’s symptoms, nutritional status or reproductive health.

These are not tests I automatically order for every couple trying to conceive.

Comprehensive Nutrient Testing

If someone’s diet, symptoms or medical history suggest nutritional deficiencies, I may look beyond the standard preconception panel.

Depending on the individual, this may include:

• RBC magnesium
• Zinc
• Copper
• Ceruloplasmin
• Selenium
• Homocysteine
• Methylmalonic acid
• Omega-3 status

Nutrients work together, so interpretation matters. For example, zinc and copper shouldn’t necessarily be viewed independently, and taking large amounts of one nutrient without understanding the bigger picture can create another imbalance.

Omega-3 Index

An Omega-3 Index measures EPA and DHA in red-blood-cell membranes and provides an estimate of longer-term omega-3 status.

EPA and DHA are important components of cell membranes and are involved in numerous aspects of human physiology. I consider this a nutritional-status marker rather than a diagnostic fertility test.

Comprehensive Stool Testing

If someone is trying to conceive and also has significant digestive symptoms, I may investigate the gut.

Examples include:

• Chronic bloating
• Constipation or diarrhea
• IBS symptoms
• Persistent reflux
• History of gastrointestinal infections
• Unexplained iron or nutrient deficiencies
• Symptoms suggestive of malabsorption

A comprehensive stool test such as GI-MAP can provide information about gastrointestinal microorganisms and certain digestive and inflammatory markers.

However, finding an abnormality on a commercial microbiome test doesn’t establish that it is causing infertility. Evidence that microbiome-directed treatment based on these tests improves fertility outcomes remains limited.

The reason to investigate the gut should come from the patient’s history—not simply the fact that they’re trying to become pregnant.

Celiac Disease Screening

This is one test I don’t want overlooked when the history fits.

Consider conventional celiac screening, such as:

• Tissue transglutaminase IgA (tTG-IgA)
• Total IgA

It may be particularly relevant when infertility occurs alongside gastrointestinal symptoms, unexplained iron deficiency, nutrient deficiencies, autoimmune disease or a family history of celiac disease.

Identifying celiac disease matters because it can interfere with nutrient absorption and has recognized associations with reproductive health.

Advanced Metabolic Testing

Someone can have an A1c within the reference range and still have evidence of early insulin resistance.

When clinically appropriate, I may consider:

• Fasting glucose
• Fasting insulin
• Hemoglobin A1c
• HOMA-IR

This can be especially useful in women with PCOS, irregular cycles or other signs of insulin resistance.

Advanced Hormone Testing

Standard serum hormone testing should generally come first.

In select cases, urinary hormone-metabolite testing such as DUTCH testing may provide additional information about hormone metabolites and cortisol patterns.

But there’s an important distinction: DUTCH testing isn’t a standard infertility evaluation, nor has it been established as a test that predicts someone’s ability to conceive.

I use specialty hormone testing to answer a specific clinical question—not as a prerequisite for pregnancy.

Oxidative Stress Testing

Oxidative stress has become an increasingly interesting area of reproductive research, particularly in male fertility.

One specialty marker is:

8-OHdG

8-hydroxy-2’-deoxyguanosine (8-OHdG) is a biomarker associated with oxidative damage to DNA.

Excessive oxidative stress can negatively affect sperm function, and sperm are particularly vulnerable to oxidative damage.

However, urinary 8-OHdG isn’t currently a standard fertility test and shouldn’t be interpreted as a measurement of someone’s ability to conceive.

I view it as an additional piece of information in selected cases rather than a standalone fertility marker.

Sperm DNA Fragmentation

A traditional semen analysis tells us about sperm number, movement and appearance—but it doesn’t directly assess the integrity of the DNA carried by those sperm.

Sperm DNA fragmentation testing evaluates DNA damage within sperm.

It isn’t recommended as a routine first-line test for every man experiencing infertility. However, fertility specialists may consider it in selected situations, including certain cases involving recurrent pregnancy loss or failed assisted-reproductive treatments.

Environmental Exposure Testing

Environmental exposures are another area where individualized testing matters.

When someone has a known occupational, environmental or lifestyle exposure, targeted testing may be appropriate.

For example, documented or suspected exposure to certain heavy metals may justify conventional testing.

What I don’t recommend is automatically ordering enormous “toxin panels” on every couple trying to conceive.

The presence of a chemical or metabolite in blood or urine doesn’t necessarily mean it is causing infertility, and some commercial environmental tests don’t have established clinical thresholds for the conclusions frequently drawn from them.

Functional Tests I Don’t Routinely Order for Everyone Trying to Conceive

Functional medicine is most useful when testing is purposeful.

I don’t believe every person preparing for pregnancy automatically needs:

• GI-MAP or another comprehensive stool test
• DUTCH testing
• Food IgG “sensitivity” testing
• Urine mycotoxin testing
• Hair mineral analysis
• Broad “detox” panels
• MTHFR testing simply because they’re trying to conceive
• Large micronutrient panels without an indication
• Oxidative-stress testing without a clinical reason

Sometimes these tests have an appropriate place. Sometimes they don’t.

A test should answer a question—and ideally, the answer should change what we do next.

Don’t Forget: Some of the Most Important Fertility Tests Aren’t Blood Tests

You can have beautiful nutrient, thyroid and hormone labs and still have a structural or sperm-related reason pregnancy isn’t occurring.

For women experiencing infertility, evaluation may also include:

• Transvaginal ultrasound
• Assessment of the uterus and ovaries
• Hysterosalpingography (HSG) or other testing of fallopian-tube patency when indicated

For men, semen analysis remains one of the most important initial tests.

Functional testing should complement—not replace—a proper fertility evaluation.

When Should You Seek a Fertility Evaluation?

If you’re simply preparing for pregnancy, preconception care can begin before you start trying.

If you’ve already been trying without success, professional fertility guidelines generally recommend evaluation after:

12 months of regular unprotected intercourse when the female partner is younger than 35.

6 months when the female partner is 35 or older.

For women over 40, a more immediate evaluation may be appropriate.

You also don’t necessarily need to wait six or twelve months when there is already a known reason fertility could be affected, such as very irregular or absent periods, suspected endometriosis or tubal disease, or known/suspected male-factor infertility.

The Bottom Line

I don’t think preconception optimization should become another reason to feel like your body isn’t “ready” or that you need thousands of dollars of testing before you’re allowed to start trying.

Instead, I look at it as an opportunity.

Do we have nutritional deficiencies we can correct?

Is thyroid function where it should be?

Are blood sugar and insulin signaling healthy?

Are menstrual cycles and ovulation behaving as expected?

Are there digestive symptoms or absorption issues that deserve investigation?

Are there medications, supplements or lifestyle factors that should be addressed?

And if pregnancy isn’t happening, have we evaluated both partners rather than focusing exclusively on the woman?

Sometimes the answer is found on a basic CBC or ferritin.

Sometimes someone’s history gives us a reason to investigate insulin resistance, gastrointestinal health, nutrient status, oxidative stress or sperm DNA integrity more closely.

And sometimes the most appropriate next step isn’t another functional lab at all—it’s a semen analysis, ultrasound or evaluation of the fallopian tubes.

The goal of functional medicine isn’t to order every test available. It’s to understand the individual in front of us, ask better questions and use testing strategically to identify the factors we can actually do something about.

This article is for educational purposes only and isn’t a substitute for individualized medical care. Preconception and fertility testing should be selected and interpreted by an appropriately qualified healthcare professional based on your individual history, symptoms and reproductive goals.