Low progesterone symptoms: what they look like in your late thirties and forties, and what's worth testing

Georgina Waugh, Clinical Nutritionist (BHSc Nutritional Medicine) · 9 minute read · Updated 12 October 2026

Your period used to turn up when you expected it. Now it’s 24 days one month and 35 the next, heavier than it used to be, and the week before it doesn’t feel like yours any more.

Most low progesterone symptom lists are describing exactly that, and there’s a plain reason for it. Progesterone is made mainly after you ovulate, and in your late thirties and forties more cycles go by without ovulation. In a study of 848 women aged 43 to 53, the share of cycles that showed ovulation fell from about 81% to 65% in three years.

So the signs mostly show up in your cycle: its length, how heavy and predictable your bleeding is, and how the second half of the month feels. It’s a change every woman goes through in the transition, not something you’ve caused. The symptoms can’t tell you on their own, though, which is why the timing of a test matters so much.

The short version

• Progesterone rises after ovulation, so a cycle without ovulation leaves very little of it that month.
• In a study of 848 women aged 43 to 53, the share of cycles that showed ovulation fell from 80.9% to 64.7% over three years.
• The signs mostly show up in your cycle: its length, how heavy and predictable your bleeding is, and the second half of the month.
• Thyroid, PCOS and not eating enough for how hard you train can lower it too, so they’re worth checking.
• A progesterone blood test is timed to about seven days before your next period, not to day 21 of every cycle.
• Start by writing down the first day of each period and how heavy your bleeding is.

What low progesterone symptoms usually look like

Your ovaries make most of your progesterone in the second half of your cycle. After an egg is released, the follicle it came from turns into a small gland called the corpus luteum, and that’s what makes it. Levels rise after ovulation and fall again just before your period.

So if you don’t ovulate in a particular month, there’s very little progesterone that month. That’s the mechanism behind almost everything on the lists you’ve been reading.

Your cycle changes length. Ovulation can come later, or not at all, so the cycle stretches out or turns up early.

Your bleeding gets heavier or harder to predict. Cycles without ovulation are one of the common reasons bleeding changes in perimenopause.

The week before your period feels different. This one is more complicated than the lists make it sound. Progesterone breaks down into allopregnanolone, which acts on the same calming receptors in your brain that alcohol and some sedatives do. In some women, the rise after ovulation is what brings on low mood and irritability before a period, rather than a lack of progesterone. Your cycle notes are what show which way it goes for you.

The sleep and mood items on most online lists are where the evidence is thinnest, so please don’t take them as the answer on their own.

Why your cycle changes in your late thirties and forties

The study I’d point you to is the Daily Hormone Study, part of a large US study that followed women through the menopause transition. 848 women aged 43 to 53 collected a urine sample every day for one cycle each year, and the lab looked for the rise in a progesterone breakdown product that follows ovulation.

In year one, 80.9% of cycles showed ovulation. By year three, it was 64.7%. The cycles with no sign of ovulation and no period within 50 days nearly tripled, from 8.4% to 24%.

From the Daily Hormone Study inside a large US study that followed women through the menopause transition. Each year, women collected urine every day for one cycle, or for up to 50 days, and the lab looked for the rise in a progesterone breakdown product that follows ovulation. “No period” means no bleed within those 50 days.

Across the three years, the progesterone breakdown product in the urine fell about 6.6% a year. Another study, which tracked women for five years, found most cycles late in perimenopause had no ovulation at all.

There’s an Australian study that shows the same thing from blood. Women gave three blood samples a week across one cycle. Only 1 of 16 women early in the transition had a cycle without ovulation. Late in the transition, it was 9 of 23.

From a University of Sydney study of healthy women followed across one cycle each. In the cycles that did ovulate, average progesterone in the second half of the cycle fell as the stages went on, while oestradiol rose. Small groups, so read the shape rather than the exact numbers.

Here’s the part that surprises people. In the cycles that did ovulate, progesterone in the second half fell as the stages went on, while oestradiol, the main oestrogen, went up. So it’s rarely a story of all your hormones dropping. More often, oestrogen is holding up or swinging around while progesterone falls behind, and that’s why it can feel so unpredictable from one month to the next.

Two things to keep in mind. These are small groups and averages, not a prediction for you. And they describe a change that happens to everyone in the transition, so there’s nothing wrong with you for feeling it.

What else can lower progesterone

Perimenopause is the most common reason, but it isn’t the only one, and more than one can be going on at once. Anything that stops you ovulating regularly lowers progesterone.

Your thyroid. Thyroid hormones are closely tied to your cycle, and an underactive thyroid is associated with periods that come further apart. It’s one of the first things worth ruling out.

PCOS. Irregular cycles and ovulating less often are one of the defining features of polycystic ovary syndrome, and insulin resistance often sits underneath it.

Not eating enough for what you’re doing. If you’re training hard and not eating enough to cover it, your body can switch off ovulation to save energy. This happens to women who’d never call themselves athletes, and it’s easy to miss when you’re eating “healthy” but small.

Stress, sleep and food, together. The things you do every day sit around all of this, which is why I look at what you’re eating, how you’re sleeping and what’s going on in your life alongside your cycle, never one hormone on its own.

What’s worth testing, and when

What I want to see first is the basic foundations: a full blood examination, iron studies including ferritin, B12, folate, a full thyroid panel with antibodies, vitamin D and zinc, plus HbA1c and fasting insulin. Heavier periods use up iron, and your thyroid and blood sugar both affect your cycle, so these matter here more than people expect.

Then there’s progesterone itself. The usual blood test is taken in the second half of your cycle, about seven days before your next period is due, and a raised level shows you ovulated that month.

That’s where “day 21” comes from, and it only fits a 28-day cycle. If your cycles run 24 days, or 35, count back seven days from when you expect your next period instead. A test on the wrong day can come back low simply because it was taken too early.

It’s also one cycle, on one morning. In the same large study, women had a timed blood test in the second half of the cycle while also collecting urine every day, and the two only lined up weakly: one explained about 7% of the variation in the other. So a single result is worth having, and worth repeating if it doesn’t match how your cycle’s behaving.

So when the hormone question is still open, we look at the pattern. The DUTCH Complete is a dried urine test you collect at home, and it can add context by looking at progesterone alongside your oestrogens, how they’re being broken down, and your cortisol across the day. It’s a test we organise after a consult, once we know it’s the right one for you.

Please see your GP if your bleeding is very heavy, comes between periods or after sex, or starts again after menopause. And if you’re pregnant, or trying to be, questions about progesterone go to your GP or fertility specialist.

What I see in clinic. The pattern I see most often is a woman in her late thirties and forties who has done her bloods, been told “everything’s normal”, and feels like her hormones are all over the place. Her cycle’s shifting, and her oestrogen is often fluctuating rather than low.

What to do this week

1. Start tracking your cycle in the notes on your phone. Write down the first day of each period, how heavy your bleeding is, any spotting, and how you sleep and feel in the week before. Two or three cycles of this tells us a lot.
2. Work out your own timing. Count back seven days from when you expect your next period, and that’s the day a progesterone test is worth doing.
3. If you’re training hard, check you’re eating enough on those days to cover it.
4. Ask your GP for the basic foundations listed above, and mention the changes in your cycle and any heavier bleeding.

When those results come back, the sentence most people hear is that everything’s normal. If that’s where you land, a Blood Test Analysis is fifteen minutes, one-on-one, going through the results you already have and showing you where your numbers are actually sitting. $79, no new test and no referral.

Here’s how we work through hormone changes with you:

1. Rule out what needs a doctor first. Very heavy bleeding, bleeding between periods and anything that’s getting worse.
2. Read your cycle notes for the pattern. How long your cycles run, and what the second half of each one looks like.
3. Check the foundations properly. Your iron, thyroid and blood sugar, read against where they should sit for you, not just the reference range.
4. Test hormones when the timing’s right. Matched to your cycle, and read alongside everything else.

And before you buy anything for your hormones, ask yourself:

• Have my cycles got shorter, longer or less predictable in the last year or two?
• Are my periods heavier than they used to be?
• Was my progesterone test timed to my own cycle, or just to day 21?
• Has anyone checked my iron studies and a full thyroid panel?
• Am I eating enough for how much I’m training?

None of this means your body’s broken. It’s doing something completely normal for your forties, it just didn’t send you a memo first!

Not sure what your cycle’s telling you?

In a free 15-minute call, I’ll go through your cycle notes, what’s already been tested and what’s going on with your energy and sleep, and we’ll work out what’s worth checking first.

Book a free 15-minute call

Fifteen minutes, on the phone, and nothing to buy to book it.

Common questions

What are the early signs of low progesterone?

The earliest signs usually show up in your cycle: cycles getting shorter or longer, bleeding that’s heavier or less predictable, or a second half of the cycle that feels different. Progesterone is made mainly after ovulation, so these changes often mean some cycles are going by without it. Symptoms alone can’t confirm it. Tracking your cycle and a test timed to it can.

Can low progesterone cause anxiety?

It’s more complicated than that. Progesterone breaks down into allopregnanolone, which acts on calming GABA receptors in the brain. In some women, the rise in progesterone after ovulation is what brings on low mood, irritability or anxiety in the week before a period. If anxiety is with you most days, please talk to your GP, and if you need someone to talk to tonight, Lifeline is 13 11 14.

What can throw off progesterone levels?

Anything that stops you ovulating regularly: perimenopause most often, plus an underactive thyroid, PCOS, and not eating enough for how hard you train. Stress, sleep and what you’re eating sit around all of these, so they’re worth looking at together rather than one hormone on its own.

How do I know if I need to increase my progesterone?

You can’t tell from symptoms alone. Track your cycles for two or three months, then have a progesterone blood test about seven days before your next period is due, alongside the basic foundations: a full blood examination, iron studies, B12, folate, a full thyroid panel, vitamin D and zinc. Whether hormone therapy is worth considering is a conversation for your GP.

What are the signs of low progesterone during pregnancy?

If you’re pregnant and worried about bleeding, cramping or your progesterone, please contact your GP, obstetrician or midwife straight away rather than relying on a symptom list. Progesterone in pregnancy is managed by your medical team.

Sources

Every study and number in this post comes from one of these.

1. Santoro N and colleagues. Factors related to declining luteal function in women during the menopausal transition. Journal of Clinical Endocrinology and Metabolism, 2008. Study of Women’s Health Across the Nation (SWAN) Daily Hormone Study; figures from Table 1.
2. Hale GE and colleagues. Endocrine features of menstrual cycles in middle and late reproductive age and the menopausal transition classified according to the Staging of Reproductive Aging Workshop (STRAW) staging system. Journal of Clinical Endocrinology and Metabolism, 2007.
3. O’Connor KA and colleagues. Progesterone and ovulation across stages of the transition to menopause. Menopause, 2009.
4. Santoro N and colleagues. Daily luteal serum and urinary hormone profiles in the menopause transition: Study of Women’s Health Across the Nation. Menopause, 2020.
5. Pathology Tests Explained. Progesterone.
6. Cable JK and Grider MH. Physiology, Progesterone. StatPearls, 2023.
7. Dreisler E and colleagues. Perimenopausal abnormal uterine bleeding. Maturitas, 2024.
8. Bäckström T and colleagues. Allopregnanolone and mood disorders. Progress in Neurobiology, 2014.
9. Krassas GE and colleagues. Thyroid function and human reproductive health. Endocrine Reviews, 2010.
10. Teede HJ and colleagues. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Journal of Clinical Endocrinology and Metabolism, 2023.
11. Mountjoy M and colleagues. 2023 International Olympic Committee’s (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). British Journal of Sports Medicine, 2023.

Important: This article is general information written by a clinical nutritionist. It's not medical advice and doesn't replace care from your GP or another qualified health professional. Functional testing is not diagnostic and doesn't diagnose, treat, cure or prevent any condition, and results are best interpreted alongside your symptoms, history, medications and supplements.

Reviewed by Georgina Waugh

Clinical Nutritionist, BHSc Nutritional Medicine

Last updated: 12 October 2026

Sources reviewed: Four studies of hormones through the menopause transition, including one from the University of Sydney, reviews of perimenopausal bleeding, mood and thyroid, the international PCOS guideline, and Australian pathology guidance on progesterone testing.