Hormones and Fertility: The Thyroid, Prolactin, and Progesterone Tests to Run First

You've been tracking your cycle for months. The ovulation strips. The app. The supplements someone in a Facebook group swore by. The timed everything. And every month, your period shows up anyway. When you finally bring it up at an appointment, the answer usually lands in one of two places: keep trying and check back in a year, or a referral to a fertility clinic with a long waitlist and a price tag that makes your stomach drop.

There's a step between those two answers that gets skipped constantly. Checking whether the hormones that run ovulation are actually doing their jobs.

Three of them cause an outsized share of the trouble: your thyroid, prolactin, and progesterone. Each one can throw off ovulation or make it harder for an early pregnancy to take hold. Each one shows up on a blood draw. And each one is routinely left out of the standard "your labs look fine" conversation.

Ovulation Is a Chain, and Every Link Has to Hold

A regular cycle depends on a sequence of signals. The hypothalamus in your brain cues the pituitary gland. The pituitary releases FSH and LH, which tell an ovary to mature and release an egg. After ovulation, the empty follicle becomes a small temporary gland called the corpus luteum, which produces progesterone to prepare the uterine lining for a possible pregnancy.

Thyroid hormone influences the pace of nearly every step in that sequence. Prolactin can quiet the signals at the very top of it. Progesterone decides whether the second half of the cycle holds. When conception is taking longer than expected, these three deserve a hard look first, because any one of them can be off while your cycle still looks almost normal from the outside.

Your Thyroid: The Most Commonly Missed Piece

The thyroid sets the tempo for metabolism, temperature, and energy, and your ovaries pay close attention to it. When thyroid hormone runs low, cycles often get longer, heavier, or unpredictable, and some cycles stop releasing an egg at all. An underactive thyroid can also nudge prolactin upward, which compounds the problem (more on that in a moment).

The signs worth noticing alongside cycle changes: fatigue that never lifts, feeling cold when nobody around you is, thinning hair, dry skin, weight that climbs without explanation, a slow drift in mood.

The catch is how thyroid usually gets tested. Standard screening checks TSH alone, a single signaling hormone sent from the brain. TSH can sit in the normal range while your body struggles to convert T4 into T3, the active hormone your cells actually run on. And a TSH-only test says nothing about thyroid antibodies, the markers of Hashimoto's, an autoimmune thyroid condition that can smolder for years before TSH ever moves. Running a TSH and calling the thyroid cleared is a box checked, not a question answered.

A real preconception thyroid workup means TSH, free T3, free T4, reverse T3, and thyroid antibodies together. Sophia Viner, DNP, ANP-BC, our board-certified nurse practitioner with more than 20 years of clinical experience in hormone care and thyroid optimization, treats that full panel as basic groundwork for any woman dealing with cycle trouble, because the patterns TSH misses are exactly the ones that matter here.

Prolactin: The Hormone Nobody Warned You About

Prolactin's main job is milk production after a baby arrives. While a mother is nursing, it runs high on purpose, and one of its built-in effects is suppressing ovulation. That part is by design.

The trouble starts when prolactin runs high and you're not pregnant or nursing. Elevated prolactin dampens the brain signals at the top of the ovulation chain, so cycles space out, turn irregular, or stop. Common causes include an underactive thyroid, chronic stress, certain medications (some antidepressants and anti-nausea drugs among them), and occasionally a small benign growth on the pituitary gland that a provider can identify and manage.

Some women get clues, like periods that vanish for months or milky nipple discharge when they're not nursing. Plenty of others have no obvious symptom beyond a cycle that won't cooperate. One blood test answers the question. Most causes are very treatable once found.

Progesterone: The Second-Half Hormone

Everything up to ovulation runs mostly on estrogen. After ovulation, progesterone takes over. It matures the uterine lining, keeps it stable, and supports the earliest days of a pregnancy. When progesterone runs low or drops too early, the second half of the cycle (the luteal phase) cuts short, and the lining can start to break down before an embryo has a fair chance to settle in.

What that can look like in real life: spotting a few days before your period arrives, cycles that consistently run short, or PMS that ramps up harder than it used to.

Timing decides whether this test means anything. Progesterone only rises after ovulation, so it has to be drawn in the middle of the second half of your cycle, roughly a week after you ovulate. A progesterone level pulled at your annual physical on a random day tells you close to nothing. A well-timed draw does double duty: it confirms you actually ovulated that cycle, and it shows whether the second half is holding.

Why This Belongs Before (and Alongside) Fertility Treatment

Fertility treatment asks a lot of you, physically and financially, before anyone can promise a result. Starting it while an untreated thyroid problem or unexplained high prolactin sits underneath means asking your body to do its hardest work on an unsteady base. Getting these systems corrected first is one of the few parts of this process fully within reach right now.

Fertility clinics do screen some of these markers. Primary care often doesn't, and primary care is where most women start. In one survey of women's health care experiences, 93 percent of women reported feeling dismissed at some point while seeking medical help. Laurie saw several OBGYNs who could not agree on her hormones before she finally got answers. We wrote about that pattern, and how to push for real testing, in Why Won't My Doctor Test My Hormones?

The rest of the picture matters too. Blood sugar and insulin problems can disrupt ovulation, which is central to polycystic ovary syndrome, recently renamed PMOS. Chronic stress reshapes cortisol, and cortisol tangles with the entire reproductive chain, which is part of what our thyroid and adrenal evaluation is built to sort out. For women in their late 30s and 40s, early perimenopause shifts can overlap with all of the above. This is the whole argument for testing widely instead of guessing one hormone at a time: functional medicine treats these systems as connected, because they are.

What a Full Preconception Hormone Workup Includes

If you're going to ask for testing, ask for the whole picture at once:

• A complete thyroid panel: TSH, free T3, free T4, reverse T3, and thyroid antibodies
• Prolactin
• Progesterone, timed to the second half of your cycle
• Estradiol, FSH, and LH
• Testosterone and DHEA-S, which flag PMOS-type patterns and shape energy and libido
• Fasting insulin and glucose, because blood sugar and ovulation are tightly linked
• Cortisol, to see what stress is doing to everything else
• Nutrient markers: vitamin D, B12, and iron stores

Our advanced testing covers this ground in a single draw as part of an 80+ biomarker panel, paired with a full body composition scan, instead of one test at a time across months of separate appointments.

How Med Matrix Approaches Hormones and Fertility

One thing to be clear about up front: Med Matrix is a functional medicine clinic in South Portland, Maine. IVF, IUI, and other fertility procedures stay with your OB or a reproductive endocrinologist, and we're glad to work alongside the care team you already have. Our work is the hormonal groundwork underneath: finding the thyroid, prolactin, progesterone, blood sugar, and stress patterns that make conception harder, and correcting them.

It starts with a free discovery call, where a patient coordinator hears what's actually been happening with your cycle and your health before anything gets scheduled. Then comes the 80+ biomarker panel, the body composition scan, and in-depth health questionnaires. Our medical team reviews all of it together, cross-referencing your symptoms and cycle history against the biomarker patterns instead of reading each lab in isolation.

From there you sit down for a full 60-minute consultation with a provider like Dr. Sasha Rose, a licensed naturopathic doctor with nearly two decades of clinical experience who works extensively with women's hormone and complex chronic cases. You go through every result together and build a plan. For some women that means targeted thyroid treatment. For others it means restoring broader hormone balance or addressing blood sugar first. The plan comes with ongoing support and lab rechecks, so it adjusts as your body responds.

This kind of testing serves you well past this season, too. The same full-picture approach guides women through perimenopause and, when the data supports it, hormone replacement therapy down the road. It's all part of our women's health program, backed by a team of 7 providers who have served 3,000+ patients with a 4.9-star rating across 150+ Google reviews. You can meet our providers before deciding anything.

Frequently Asked Questions

Should I get my thyroid tested before trying to conceive?

Yes, and get it tested fully. Thyroid problems are among the most common and most correctable hormone issues affecting cycles, and they frequently cause no obvious symptoms early on. Ask for TSH, free T3, free T4, reverse T3, and thyroid antibodies, not TSH by itself.

My doctor checked my TSH and said it was normal. Is that enough?

Not on its own. TSH is a signal from the brain, not a measure of the active thyroid hormone your cells use. A normal TSH can sit on top of a conversion problem (T4 that never becomes active T3) or antibody activity from autoimmune thyroid disease that TSH won't reveal until much later. The full panel exists because TSH alone misses those patterns.

What does prolactin have to do with getting pregnant?

Elevated prolactin suppresses the brain signals that start ovulation. When it runs high outside of pregnancy and nursing, cycles turn irregular or stop entirely. It's a single blood test, and the common causes, including thyroid problems, stress, and certain medications, are usually manageable once identified.

When in my cycle should progesterone be drawn?

Roughly a week after you ovulate, in the middle of the luteal phase. The anchor is your ovulation day, not a fixed calendar date, which is why cycle tracking helps your provider time the draw. Drawn at the right moment, one progesterone level confirms ovulation and shows whether your luteal phase is holding.

Does Med Matrix do fertility treatment?

No. Procedures like IVF and IUI belong with your OB or a reproductive endocrinologist. Our role is the hormone testing and correction underneath that care: thyroid, prolactin, progesterone, blood sugar, cortisol, and nutrients, mapped together and addressed before or alongside whatever your fertility team recommends.

What does the full workup cost?

New-patient onboarding runs approximately $1,200 to $1,500 all-in, covering the 80+ biomarker panel, body composition scan, provider review, and a full 60-minute consultation. Follow-up visits are $275, and new patients receive a $100 voucher. We accept HSA, FSA, CareCredit, and all major cards.

Months of negative tests wear you down in a way that's hard to explain to anyone who hasn't lived it. Before you resign yourself to a waitlist or chalk it up to bad luck, find out what your hormones are actually doing. Start Getting Real Answers with a free discovery call and a full hormone panel read by a provider who has the time to go through every result with you.