The Missing Piece in Your Fertility Journey: Progesterone

What is Progesterone?

Progesterone is the hormone made after ovulation that naturally rises during the second half of your menstrual cycle, also known as the luteal phase. You may have heard progesterone referred to as the “pregnancy hormone” because it prepares your body for a potential pregnancy each cycle. (2)

Why is Progesterone Important for Fertility?

Think of progesterone as the hormone that “sets the stage” for pregnancy. After ovulation, progesterone matures and stabilizes the uterine lining, and makes it receptive to implantation, essentially preparing a cozy place for a fertilized egg to implant and grow. (3)

When progesterone levels are too low, that lining may not be stable enough, which is associated with lower implantation rates and an increased chance of early miscarriage. Low progesterone is also often a sign that ovulation isn’t happening as effectively or consistently as it should be, and since progesterone is produced after ovulation, the two are closely connected. (2, 4)

The good news? Things like what you eat, how much you’re fueling your body, and how you manage stress can all play a role in supporting healthy progesterone levels. We’ll walk through each of these below.

Ways to Boost Progesterone Naturally

Nutrients

Omega-3 Fats

Omega-3 fatty acids may boost progesterone levels and ovulation. Some research has found that women with higher omega-3 intake tend to have higher progesterone levels and a lower risk of missed ovulation. (5, 6) In certain cases, omega-3 supplementation has also been linked to improvements in progesterone levels and overall hormone balance. (6) To help support hormone balance, try including more omega-3-rich foods in your diet:

● Flaxseed

● Chia seeds

● Walnuts

● Fatty fish like salmon, tuna, and sardines 7

Vitamin C

Vitamin C may play a helpful role in supporting progesterone levels and overall fertility. Some research has found that higher vitamin C levels are linked to increased progesterone during the luteal phase, and supplementation may help improve progesterone levels. (8, 9, 10)

One reason for this may be its role as an antioxidant. Vitamin C helps protect cells in the ovary from oxidative stress, which can interfere with hormone production. It’s also involved in the production of steroid hormones, including progesterone, and may support healthy ovulation by helping the egg develop and be released properly. (8, 9, 10)

Adding vitamin C-rich foods into your routine is a simple way to support overall reproductive health. Foods high in vitamin C include:

● Oranges

● Lemons

● Strawberries

● Bell peppers

● Broccoli

● Kale

● Tomatoes

● Guava

● Kiwi 11

Moderate Fiber Intake

Fiber is an important part of a healthy diet, but very high intakes may impact reproductive hormones. Some research has found that higher fiber intake was associated with lower progesterone levels compared to more moderate intake. (12, 13)

One reason for this may be fiber’s effect on the gut. Higher fiber intake can influence how hormones are processed in the body, which may lead to lower circulating hormone levels.

High-fiber diets have also been associated with lower estrogen levels, which may indirectly affect progesterone. (14, 15)

For women trying to conceive, the goal isn’t to avoid fiber, but to aim for a balanced, moderate intake while still meeting overall nutrition needs. Because fiber needs can vary, working with a dietitian can help you find an intake that supports both overall nutrition and hormone health.

Even with a moderate fiber intake, you can still include plenty of nutrient-dense foods such as:

● Well-cooked vegetables (like carrots or green beans)

● Soft fruits

● Dairy products

● Eggs

● Lean proteins (16)

Not sure how to incorporate these nutrient recommendations into your diet? Here are a few recipes to get you started!

● Citrus-Seared Salmon

● Chicken and Tomato Rice Soup

● Pasta Tuna Salad with Lemon Yogurt Dressing

● Eggs and Citrus Smoothie Combo

Energy Availability

Energy availability refers to the amount of energy your body has left after supporting daily functions like breathing, talking, thinking, and organ function, in addition to exercise. If energy intake doesn’t fully match these demands, the body may try to save energy by decreasing certain processes, like hormone production. (17, 18, 19) Higher levels of physical activity have been associated with lower progesterone levels, with one study showing 22% less luteal progesterone in more active women compared to less active. (17) However, this likely reflects low energy availability, rather than exercise itself. Research shows that low energy availability is linked to ovulatory disturbances and lower progesterone, and even moderate exercise paired with a calorie deficit can reduce hormone levels. (17, 18, 19)

For women trying to conceive, this doesn’t mean avoiding exercise, but rather finding a balance. Regular movement is beneficial, but excessive training without adequate fueling may negatively impact hormone production. Prioritizing enough food intake, especially during periods of higher activity, can help support healthy ovulation and progesterone levels. Since energy needs vary for everyone, working with a dietitian can help you determine how much to eat to support your activity and hormone health.

If you want to understand how this applies to your cycle specifically, my free private podcast is a great place to start.

Stress

Stress can also play a significant role in hormone balance and fertility. Higher levels of stress, and the associated increase in cortisol (the stress hormone), have been linked to lower progesterone levels and disruptions in ovulation. (20, 21) In fact, one study found that higher daily stress was associated with a ~10% decrease in luteal progesterone and more than double the odds of not ovulating. (20)

This may be due to stress hormones interfering with the brain signals that trigger ovulation. Elevated cortisol can reduce the release of key reproductive hormones like luteinizing hormone and estrogen, ultimately disrupting the menstrual cycle and lowering progesterone levels. (20, 21)

Managing stress is an important (and often overlooked) part of supporting hormone balance. Adding simple habits can help regulate stress levels and support overall reproductive health:

● Walking

● Spending time outside

● Journaling

● Meditation

● Prioritizing sleep (22)

Key Takeaways

● Eat enough to support your activity level

● Include omega-3s and vitamin C-rich foods

● Aim for moderate fiber intake

● Manage stress to support hormone balance

● Keep exercise balanced and well-fueled

Progesterone reflects your overall lifestyle, not just one habit or nutrient. Focusing on balance in nutrition, movement, and stress can help support healthy hormone levels and reproductive function.

Developed with student researcher Lexi Harrison, MS in Human Nutrition, University of Delaware.

References:

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https://www.ncbi.nlm.nih.gov/books/NBK279054/

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Beginning of Life. Int J Mol Sci. 2022;23(22):14138. Published 2022 Nov 16.

doi:10.3390/ijms232214138

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phase length and natural fertility. Fertil Steril. 2017;107(3):749-755.

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serum adiponectin and fertility hormones in women with polycystic ovarian syndrome. J

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Serum Reproductive Hormones and Ovulation among Healthy Women. J Nutr.

2016;146(1):98-106. doi:10.3945/jn.115.217620*

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Fertil Steril. 2003;80(2):459-461. doi:10.1016/s0015-0282(03)00657-5*

10. Schliep KC, Schisterman EF, Mumford SL, et al. Energy-containing beverages:

reproductive hormones and ovarian function in the BioCycle Study. Am J Clin Nutr.

2013;97(3):621-630. doi:10.3945/ajcn.111.024752*

11. National Institutes of Health, Office of Dietary Supplements. Vitamin C: fact sheet for

health professionals. Updated July 31, 2025. Accessed April 6, 2026. Vitamin C Fact

Sheet

12. Andrews MA, Schliep KC, Wactawski-Wende J, et al. Dietary factors and luteal phase

deficiency in healthy eumenorrheic women. Hum Reprod. 2015;30(8):1942-1951.

doi:10.1093/humrep/dev133*

13. Gaskins AJ, Mumford SL, Wactawski-Wende J, Schisterman EF. Effect of daily fiber

intake on luteinizing hormone levels in reproductive-aged women. Eur J Nutr.

2012;51(2):249-253. doi:10.1007/s00394-011-0207-2*

14. Goldin BR, Adlercreutz H, Gorbach SL, et al. Estrogen excretion patterns and plasma

levels in vegetarian and omnivorous women. N Engl J Med. 1982;307(25):1542-1547.

doi:10.1056/NEJM198212163072502*

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Published 2012 Dec 21. doi:10.1186/1479-5876-10-253*

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https://www.cancer.gov/about-cancer/treatment/side-effects/nutrition/low-fiber-foods

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menstrual cycle on reproductive function. Ann Epidemiol. 2014;24(2):127-134.

doi:10.1016/j.annepidem.2013.11.002*

18. Castellanos-Mendoza MC, Galloway SDR, Witard OC. Free-living competitive

racewalkers and runners with energy availability estimates of <35 kcal·kg fat-free mass-

1·day-1 exhibit peak serum progesterone concentrations indicative of ovulatory

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Nov 17. doi:10.3389/fspor.2023.1279534*

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and ovulatory function: a prospective cohort study. Epidemiology. 2015;26(2):177-184.

doi:10.1097/EDE.0000000000000238*

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A. Interactions of Cortisol and Prolactin with Other Selected Menstrual Cycle Hormones

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Accessed April 6, 2026. https://www.cdc.gov/mental-health/living-with/index.html

Are You Actually Ovulating?

Ovulation & Hormone Health | Kelli O'Brien, MS, CNS, LDN

Here's something that surprises a lot of the women I work with: having a period every month doesn't automatically mean you're ovulating. It means you're having a period. Those two things are connected — but they're not the same thing.

Ovulation is the main event. Your period is what follows — whether ovulation went smoothly or not. So if you've been tracking your cycle and assuming everything is fine because you bleed pretty regularly, this post is worth a read.

"A regular period tells you your uterus is doing its job. It tells you almost nothing about whether you ovulated."

Why It Actually Matters

When ovulation doesn't happen consistently, your body doesn't make much progesterone in the second half of your cycle. And progesterone isn't just a fertility hormone — it's the one that helps you feel calm, sleep well, and keep PMS manageable. When it's low or missing, you feel it.

That might look like: brutal PMS every month, anxiety that spikes right before your period, trouble sleeping in those two weeks leading up to it, spotting before your period actually starts, or just generally feeling like your cycle is unpredictable and hard to read. These things aren't random — they're often signs that ovulation isn't happening the way it should.

What Ovulation Actually Looks Like

Each month, your body works to develop and release an egg. When everything lines up, that release happens — and what's left behind starts producing progesterone to support the rest of your cycle. Simple enough in theory, but a lot has to go right for it to happen.

When it's working well, you'll usually notice a clear temperature rise after ovulation, stretchy cervical mucus around the time of ovulation, and a second half of your cycle that lasts at least 10–12 days before your period starts. When it's not working well, those signs are faint, inconsistent, or missing entirely.

Signs ovulation may have occurred:

• A sustained temperature rise (BBT) that holds for 10+ days after ovulation

• Egg-white cervical mucus in the days leading up to ovulation

• A positive result on an ovulation predictor kit (OPK)

• A progesterone blood test showing a healthy level around 7 days after ovulation

• Mild mid-cycle cramping or light spotting around the time of ovulation

• A second half of your cycle that's at least 10–12 days long

Why Tracking Apps Often Miss It

Most period apps predict ovulation based on your past cycle length — not on anything your body is actually doing right now. They assume you ovulate on day 14. But if your cycle is longer, shorter, or varies from month to month, that estimate is often way off.

Ovulation predictor kits (OPKs) are more helpful, but they only detect a hormone surge — not the actual release of an egg. Some women, especially those with PCOS, can have that surge without ovulation actually following. The surge is just a signal. Ovulation is the outcome. They don't always go hand in hand.

What BBT tracking can tell you

Taking your temperature first thing in the morning — before getting up or checking your phone — is one of the simplest ways to get real information about your cycle. If ovulation happened, you'll usually see a clear and sustained temperature rise in the second half of your cycle. No shift? That's worth paying attention to.

Getting a progesterone test

A simple blood test about a week after you think you ovulated is one of the clearest ways to confirm it actually happened. Many providers will call your result "normal" if it clears a pretty low bar — but in my experience, a truly healthy ovulation tends to look quite a bit higher than that minimum. If your number is low, that's not a reason to panic — it's a useful clue that something earlier in your cycle needs some support.

A tool I often recommend: the Inito monitor

One of my favorite at-home tools is the Inito hormone monitor. Unlike a standard OPK, Inito tracks multiple hormones — including estrogen and progesterone — right from home, and gives you actual numbers rather than just a positive or negative line. That means you can see whether your hormones are rising and falling the way they should throughout your cycle, without waiting on a lab. For women who want more information about what's actually going on, it's a really useful option. Use this link to get a discount.

Common Reasons Ovulation Gets Disrupted

If ovulation isn't happening reliably, tracking is a starting point — but it doesn't tell you why. That's where the real work begins. In my practice, I see a handful of patterns come up again and again:

1. Blood sugar imbalances — When your blood sugar is constantly swinging up and down, it disrupts the hormonal signals your body needs to ovulate. This is one of the most common drivers I see, and one of the most overlooked.

2. Chronic stress — Your body is wired to hold off on reproduction when it senses that things aren't safe or stable. Long-term stress — even the low-grade, everyday kind — can quietly suppress ovulation over time.

3. Thyroid issues — Even mild thyroid imbalances can throw off your cycle and shorten the second half. A basic thyroid panel doesn't always catch the full picture.

4. Not eating enough — Your body needs adequate food and fuel to support ovulation. Undereating — even without following a strict diet — can signal that things are too lean for reproduction right now.

5. Hormone imbalances like PCOS — Elevated androgens (like testosterone) can interfere with how follicles develop, so eggs start to grow but don't fully release.

These patterns often overlap and reinforce each other. The good news is that when you identify which ones are driving things for you, there's a lot nutrition and lifestyle changes can do to shift them.

Where to Start If You're Not Sure

If you haven't tried BBT tracking yet, that's a free and surprisingly informative place to begin. If you want lab data, ask your provider about a progesterone test timed to your actual cycle — ideally around a week after you think you ovulated, not just a standard day 21 draw.

If either of those shows that ovulation isn't happening the way it should, that's useful information — not a reason to spiral. It means there's something worth looking into, and usually a clear path forward once you know what's driving it.

That's exactly the kind of work I do with clients. Not throwing supplements at a cycle that isn't functioning, but figuring out what's actually going on — and building a real, practical plan from there.

Want to go deeper?

The Ovulation Restoration Method is my private podcast series that walks you through exactly how to figure out why your cycle is off — and what to do about it. It's free to access, and you can listen whenever it works for you.

DM me the word OVULATE on Instagram @kelliobriennutrition and I'll send you the link directly.

Kelli OBrien, MS, CNS, LDN is a Licensed Dietitian and Certified Nutrition Specialist specializing in fertility nutrition.

Ovulation Is a Metabolic Event (And Why No One Talks About It)

If you've been tracking your cycles, timing everything carefully, and doing all the right things, and your body still isn't cooperating, I want to offer you a different way to look at what's going on.

Most fertility advice focuses on hormones.

Stimulate them. Measure them. Inject them. Override them.

But very few people are talking about this:

Ovulation is a metabolic event.

And if metabolism isn't functioning well, ovulation often won't either.

So why isn't this part of the standard fertility conversation? Because metabolism is slower to address than prescribing a medication, because it requires looking at lifestyle, stress, nourishment, and long-term patterns, and because it's harder to measure in a single lab value.

And because conventional care often separates hormones from the systems that regulate them.

But you cannot separate hormones from metabolism.

You Can't Separate Hormones from Metabolism

Hormones don't operate in isolation.

They are built, activated, converted, transported, and cleared through complex metabolic pathways, and every one of those processes requires adequate energy intake, stable blood sugar, sufficient micronutrients, healthy liver function, and a regulated nervous system.

If metabolism is off, hormone signaling is off, and if hormone signaling is off, ovulation may not happen, or may not happen consistently.

You Can Have a Period Without Ovulating

Many women are never told this.

It's possible to bleed without actually ovulating, which is called an anovulatory cycle.

Here's what that means in practice. If you are not getting a period at all, you are definitely not ovulating. If you are getting irregular bleeds, that does not automatically mean ovulation occurred. Ovulation only happens once per cycle, and pregnancy is only possible around the time of ovulation, so if ovulation isn't happening, timing intercourse won't solve the root issue.

There's another reason this matters so much. Ovulation is what triggers progesterone production. After the egg releases, the follicle it leaves behind becomes a structure called the corpus luteum, and that is what produces the progesterone your body relies on to support the second half of your cycle and a potential pregnancy. No ovulation means very little progesterone, which is why anovulatory cycles can show up as a short luteal phase, spotting before your period, or trouble holding a pregnancy.

Multiple LH Surges Do Not Mean Multiple Ovulations

If your ovulation predictor kits are showing multiple LH surges, several peaks in one cycle, or positive tests without confirmed ovulation, that does not mean you ovulated multiple times.

Ovulation happens once per cycle.

What's often happening is that your body attempts to ovulate but doesn't complete the process, so your brain sends another LH signal and tries again.

This is common with PCOS, blood sugar dysregulation, chronic stress, undereating, and post-pill transitions.

Your body is not broken. It's attempting to respond to its environment.

Ovulation Requires Safety

From a biological standpoint, ovulation is optional. Survival is not.

If your body perceives stress, whether from underfueling, unstable blood sugar, inflammation, or chronic fight-or-flight, it may suppress ovulation.

Not because it's defective. Because it's adaptive.

For ovulation to occur consistently, your body needs adequate caloric intake, blood sugar stability without chronic spikes or crashes, sufficient protein, micronutrient sufficiency, and a regulated nervous system.

Ovulation reflects metabolic safety.

Metabolic Factors That Can Disrupt Ovulation

Some of the most common contributors include the following.

Undereating or over-exercising. A chronic energy deficit signals to your brain that this is not a safe time to reproduce. As someone who once went 8 months without a period in my dieting phase, I can personally attest to this, but even mild calorie deficits can disrupt ovulation…and the signs are much more subtle than period loss.

Insulin resistance. Insulin directly affects ovarian function and hormone production.

Blood sugar dysregulation. Both elevated glucose and the kind of blood sugar crash known as reactive hypoglycemia can disrupt hormone signaling.

Micronutrient deficiencies. Low intake, restrictive dieting, poor gut absorption, or long-term birth control use can deplete the nutrients ovulation depends on.

Impaired hormone clearance. Your liver metabolizes hormones, so when those pathways are sluggish, hormone balance suffers.

Chronic stress. Your nervous system communicates directly with your reproductive system, and chronic stress shifts resources away from reproduction.

Do You Always Need Medication?

Medication absolutely has a place.

But in many cases, the deeper issue isn't that the ovaries don't work. It's that the metabolic environment isn't optimal.

When we improve blood sugar stability, nutrient status, energy availability, and nervous system regulation, ovulation often becomes more consistent.

Not because we forced it. Because we supported it.

If You're Not Sure Whether You're Ovulating…

If you have irregular cycles, see multiple LH surges, have PCOS, have been told everything looks normal, or have been trying to conceive month after month without success, the real question underneath all of it is the same: is ovulation actually happening, and if it isn't, why?

That question has an answer.

Ovulation is not random. It is a reflection of your metabolic health, and when we support metabolism, hormones tend to follow. But you cannot build a plan around a guess, so the first step is getting clear on what your body is actually doing.

That is exactly what the Fertility Audit is for.

In one 60-minute call, we look at your cycles, your symptoms, and your labs together, and I help you understand what is really happening with your ovulation and what is driving it. Afterward, I record a personalized protocol for you on video, so you leave with specific next steps you can actually follow instead of another pile of generic advice.