Progesterone has spurred a lot of attention with some popular authors claiming it can perfectly balance hormones in women, reduce “estrogen dominance”, and delay aging. But few people know what natural progesterone is or how it differs from its synthetic cousins. Read on to find out, along with its health effects and detailed information about the progesterone blood test.
What is Progesterone?
Progesterone is a sex hormone mainly produced by the ovaries, and less so by the placenta and adrenal glands. Also known as the “pregnancy hormone“, it prepares women for pregnancy and is essential to maintain it. In fact, that’s how progesterone got its name, which translates to “for pregnancy” from Latin (pro gestatio) [1+].
Progesterone is thought to be a female sex hormone. Aside from sustaining fertility and enabling a healthy pregnancy, it also prepares milk-producing glands for breastfeeding. In non-pregnant women, progesterone balances the menstrual cycle [2+, 1+].
But men also produce this hormone, although in smaller quantities and without cyclical variations. Women face changing progesterone levels every month with each phase of the menstrual cycle [2+].
Progesterone is not just a sex hormone, though. It’s one of the curious signals our body uses to achieve wide-ranging effects well beyond reproduction. Naturally-released progesterone protects brain cells from injury, increases their myelin insulation, and aids the activity of neurotransmitters [2+].
In the fetus, progesterone reduces oxidative stress and immune overactivity. Progesterone helps to create new brain cells and some of the first neuronal connections and branches in the developing fetal brain [2+].
For these reasons, progesterone can rather be considered a “neurosteroid” and is being investigated for reducing brain damage after stroke and traumatic injuries (TBIs) [2+].
This post will cover everything you need to know about progesterone, including:
- Why natural progesterone production is important and how it works
- The differences between natural and synthetic progesterone
- The benefits and risks of progesterone (both naturally produced or taken as a supplement/prescription)
- Forms of progesterone (creams, pills) and where you can get them
- The progesterone test, how to interpret your results and how to balance your levels without taking progesterone
Cholesterol is the starting point for making all steroid hormones, including progesterone. Cholesterol carried through the blood as LDL cholesterol is released in its free form into tissues, such as the ovaries. At this point, an important hormone-balancing cascade takes place:
- Cholesterol is converted to pregnenolone (in the mitochondria)
- Pregnenolone is released and transformed into progesterone
- Both pregnenolone and progesterone can also be converted to glucocorticoids like cortisol, estrogen, DHA, or male sex hormones (androgens)
All sex hormones are produced using this versatile pathway, regardless of the location in the body. The main difference is what hormones will be produced in larger quantities, and that’s where the ovaries, testis, adrenals, brain, or placenta differ [1+].
Organs that produce steroid hormones normally work in synchrony to maintain health. But many factors – from diet and stress to aging and abnormal levels of a certain hormone – can easily shift the focus of this pathway and trigger hormonal imbalances.
Progesterone in the blood mostly originates from the ovaries, while progesterone in the adrenals is usually turned into cortisol.
Progesterone doesn’t stay in the blood for long. It is bound to proteins and quickly reaches the liver to be metabolized (into sulfates and glucuronides). Its breakdown products are then removed from the body by urine [1+].
In Ovaries (Menstrual Cycle Phases)
The ovaries are unique in their cyclical activity, unlike the testes that stay more or less constant all the time.
Hormones produced by the ovaries, including progesterone, will vary based on the phase of the menstrual cycle. The release of pituitary hormones FSH and LH that orchestrate the activity of progesterone and estrogen is also in synch with these cycles .
The most important stages of the menstrual cycle flow in the following order :
- On the first day of the menstrual cycle (first day of menstruation) estrogen and progesterone release from the ovary is low. As a result, FSH starts to slowly increase.
- During the first phase of the cycle, estrogen production in the ovary starts to increase but progesterone stays low.
- LH and estrogen peak during ovulation while progesterone only mildly rises. Ovulation marks the middle of the menstrual cycle.
- The second phase of the menstrual cycle, which follows after ovulation, is dominated by progesterone. If the mature egg (follicle) released during ovulation is not fertilized, it is remodeled to form the corpus luteum or “yellow body”.
- During the last phase of the cycle, the yellow body starts to break down, and both progesterone and estrogen decline.
- The drop in progesterone and estrogen triggers another rise in FSH secretion and a new cycle begins all over again.
After menopause and as ovulation ceases, progesterone levels drop. This is because the main source of progesterone, the yellow body, is no longer being formed in the ovaries. In postmenopausal women, progesterone continues to be produced only in the adrenals in much smaller amounts.
Fertility and Pregnancy
The female body undergoes a fascinating and complex coordination of hormonal events to establish and maintain pregnancy .
Healthy progesterone levels are essential for maintaining fertility in women, along with other hormones.
The Implementation Phase
Progesterone’s role is to make the tubes better prepared to carry the fertilized egg and the uterus better prepared for its implementation. During the so-called “implementation window”, which is open for about 5 days around ovulation, progesterone makes the uterus more receptive to attaching a fertilized egg .
If your progesterone levels out of balance, your tubes and uterus might not be receptive to transporting and attaching a fertilized egg.
After the implementation phase, progesterone helps maintain pregnancy and prevents unwanted ovulation. One of its crucial roles is to shift the production of progesterone to the placenta, which happens 6 – 7 weeks into pregnancy. Shortly before pregnancy, progesterone was being produced in the yellow body that’s no longer needed .
Progesterone alone can maintain a pregnancy at the beginning. Given to women who can’t produce it (due to surgical removal) during the first trimester, progesterone maintains a pregnancy that would otherwise cause miscarriages .
If your progesterone levels are abnormal, you may be more likely to experience recurrent miscarriages.
After the third trimester, the placenta takes on full responsibility for making progesterone. As pregnancy progresses, progesterone and estrogen levels continue to rise, spiking in the last trimester. Together, these two hormones stimulate the growth of breast tissue and milk glands, preparing the body for lactation. Estrogen also increases the number of progesterone receptors in breast tissue, making the breasts more sensitive to its effects.
In late pregnancy, high progesterone and estrogen trigger the release of prolactin from the pituitary. Prolactin is the main hormone that enables milk production (pro= increasing lactin=milk production) .
Throughout pregnancy, progesterone relaxes the uterus and prevents contractions. Shortly before and during labor, progesterone activity drops while estrogen increases, triggering contractions. For example, substances that oppose the effects of progesterone (progesterone receptor antagonists) can trigger labor in the third trimester .
Abnormal progesterone levels during late pregnancy can affect breast tissue, milk glands, and uterus.
Progesterone in Men
Much less is known about the function of progesterone in men than in women. While in fact, men and women in the first phase of the menstrual cycle have very similar progesterone levels .
We know that in men, progesterone is produced in the adrenal cortex and in the testes in small amounts. It serves to balance testosterone and estrogen, impacting the production of both sperm and testosterone in the testes [5, 2+].
Very low progesterone blood levels in men are linked to obesity, a higher BMI and waist circumference. Low levels of the male sex hormone DHEA-S were directly linked to low progesterone in this study. In obese men, low progesterone may be a result of an underactive adrenal cortex .
On the other hand, high progesterone or an increased number of progesterone receptors in men can be detrimental.
In tissue samples from over 500 men, prostate cancer cells had more progesterone receptors. The density of these receptors was linked to poorer prostate cancer outcomes. Progesterone receptors have the potential to be used in diagnosing benign vs. malignant prostate cancers [7, 5].
Interestingly, progesterone may play a role in making men more hostile toward their children.
In mice, progesterone worsened aggression toward infants. Mice that can’t produce progesterone completely lack aggression and become more active caretakers of their infants! However, many other factors can affect aggression in men, especially during the parenting phase. Simply lowering progesterone levels is unlikely going to make men better and more caring fathers .
- Helps with menopausal symptoms
- Reduces stress & anxiety
- Improves energy and sleep
- May protect the brain
- There are many safer natural ways to support the body in producing progesterone
- May cause dizziness, headaches, and painful/tender breasts
- Synthetic progestins increase the risk of breast cancer
Synthetic vs. Natural Progesterone
We often hear about products with natural progesterone vs. the so-called “synthetic” progesterone. This can cause a lot of confusion, as additional terms are thrown in such as “bioidentical progesterone” or “naturally-sourced progesterone”. And to make everything even more perplexing, you may sometime also hear the term “progestins” being used.
- Natural progesterone is biochemically identical to progesterone produced by the body.
- Synthetic progesterone is made by chemically modifying the naturally-occurring progesterone molecule. Some of these drugs are even made by modifying testosterone. Technically speaking, these new molecules are no longer progesterone but are instead called “synthetic progestins”. They mimic some of the effects of progesterone but also have some different actions.
- Progestins are an umbrella term that covers both natural progesterone and synthetic progestins.
Commonly used synthetic progestins include:
- Medroxyprogesterone acetate and Dydrogesterone (created by modifying progesterone)
- Levonorgestrel and Drospirenone (created by modifying testosterone)
Synthetic progestins are often used in hormonal replacement therapy (HRT) and have spurred a lot of attention due to increasing the risk of breast cancer. A recent analysis of over 86k postmenopausal women found that natural progesterone combined with estrogen is linked to a lower breast cancer risk compared to synthetic progestin. Another observational study of 100k French women had similar results [9, 8].
Natural progesterone is the original progesterone molecule, which gave birth to the term “bioidentical” – the same as what the body makes. But are these products actually natural? The truth is that even this form of progesterone is semi-synthetic. Plants don’t make progesterone but similar compounds that need to be converted into progesterone in the lab .
How is natural progesterone made and is it safe?
The starting point for making bioidentical progesterone is either of the two plant compounds: diosgenin from an inedible Mexican yam (Dioscorea villosa) or stigmasterol from soybeans (Glycine max). Once synthesized, progesterone can be forwarded to manufacturers or compounding pharmacies that often prepare various formulations of bioidentical hormones .
Natural progesterone is micronized, which means that it’s made into a very fine powder. It can be filled into capsules (Prometrium) or formulated into creams, vaginal gels, and suppositories.
Despite a couple of studies indicating that natural progesterone may carry less risk than synthetic progestins, the research is sparse. Most of the hype originates from a couple of avid doctors who promoted it and popular books on the subject. However, natural progesterone may be safer but is not completely harmless. It is no panacea but a hormone that needs to be thoroughly tested in clinical trials [8, 9].
Health Effects of Progesterone
1) Hormonal Menopausal Therapy
Menopausal hormone therapy (MHT) can effectively reduce symptoms of menopause. It consists of estrogen and progestins to compensate for their declining levels in women with an intact uterus .
MHT may help with hot flashes, mood swings, insomnia, night sweats, vaginal dryness, and restlessness. Various combinations of natural or synthetic estrogens or progestins can be used, which are all linked to different health risks and benefits .
Breast Cancer Risk
Most of the claims about the increased risk of breast cancer span from misinterpreting cellular, animal, and human studies on premenopausal women. Additional misinterpretation spans from assuming synthetic and natural are the same .
Synthetic estrogens (conjugated equine estrogens) and synthetic progestins (medroxyprogesterone acetate) have been associated with an increased risk of breast cancer, especially when compared only to synthetic estrogens .
In contrast, natural progesterone and estrogen did not increase breast cancer risk in large observational studies. These were carried out in France and included over 100k women who were followed up for 6 – 9 years [12, 9, 8].
Cancer of the Uterine Lining
Before menopause, the uterus lining sheds with each menstruation. After menopause, the uterus stops receiving hormonal signals to shed. Estrogen alone can trigger overgrowth in the uterus and lead to cancer without progesterone to balance its effects. Adding progesterone to MHT protects the uterus lining, thins it, and lowers the risk of cancer (endometrial) .
This also explains why women who had their uterus surgically removed probably won’t benefit from progesterone. It’s still possible that the combination of both may have other benefits for women without a uterus, but these clinical studies haven’t confirmed it.
A link also exists between obesity and progesterone levels. Obese women are more likely to be progesterone-deficient, which increases their risk of endometrial cancer .
An interesting finding was that natural, oral progesterone acts differently than its synthetic cousins. It reduces cell overgrowth in the uterus (i.e. it’s antiproliferative) while synthetic progestins don’t. Vaginal natural progesterone also can’t par with the oral form. Both oral synthetic forms and the vaginal natural form only trigger secretory changes in the uterus .
How progesterone cream acts, on the other hand, is much less clear.
Natural Progesterone Cream
Unlike the pills, creams with natural progesterone usually don’t require a prescription and some women prefer them. The cream is still considered an “alternative” to the pills, as fewer studies have confirmed its effects and the ones that have been carried out had inconsistent results .
Applied on the skin, progesterone should be absorbed and have similar effects as the oral form. It has been tested for hot flashes, with one study finding a positive effect and another no effect. In one study of 54 women, a cream with natural progesterone and estrogen did relieve menopausal symptoms. But progesterone blood levels remained lower than expected .
The cream is also promoted to treat and prevent osteoporosis and as a general health tonic. However, most of the claims rely on studies with progesterone pills. New studies using the cream are desperately needed to determine its effects compared to the pills .
2) Reduces Brain Inflammation
Once scientists realized that female animals improve better than males after brain injuries, they started wondering how female sex hormones might play a role in brain protection. In brain cells exposed to LPS (the toxin that often sneaks into the blood of people with leaky gut), progesterone reduced key inflammatory markers (NF-kB, TNF-alpha, COX-2, iNOS) .
In animal studies, progesterone enhanced the integrity of the blood-brain barrier. Combined with its anti-inflammatory action, it may help heal a damaged, “leaky”, blood-brain barrier [1+].
One metabolite of progesterone (allopregnanolone) increased the production of the insulating myelin in brain cells, which may prevent Alzheimer’s disease worsening [1+].
3) May Reduce Aggression and Anxiety
Given its large impact on the brain and behavior, it’s no wonder that progesterone is considered a “neurosteroid”. Progesterone may increase caretaking behavior and relaxation. Increased levels of this hormone after giving birth may explain why breastfeeding female mice become less aggressive [1+].
Progesterone may activate GABA receptors – our the brain’s calmness sensors. It’s being researched as an alternative for reducing aggression in people with psychiatric disorders, depression, and anxiety [1+].
Although one small study of 43 women with PMS didn’t find any link between progesterone levels and anxiety, larger studies may be needed. Larger drops in progesterone may shed light on why some women become more “hostile” during PMS even if they don’t experience typical anxiety symptoms [17, 1+].
Progesterone levels in the amygdala, the region of the brain that registers fearful stimuli, may be one key to this mystery. Rats given progesterone directly into the amygdala experienced less anxiety, fear, and pain .
On the other hand, synthetic progestins found in birth control pills might contribute to low mood and libido .
4) Improves Sleep and OSA
Progesterone helps with sleep onset, sleep quality, and helps maintain normal breathing during sleep. It has been linked to improved symptoms of obstructive sleep apnea (OSA) in men and menopausal women with obesity .
In a trial of 8 postmenopausal women, progesterone (300 mg/day) restored normal sleep in those who suffered from sleep disturbances. Progesterone increased the most restorative, deep, slow-wave sleep by 50%. It didn’t sedate women who were already sleeping well, suggesting that it’s not a sedative but rather a balancing hormone .
5) Improves Mood, Cognition, and SSRI Response
Progesterone and other sex hormones shape the brain and increase its plasticity throughout its lifetime. Progesterone is especially important for mental health in women. Receptors for this hormone are located all along the areas of the brain involved in cognition, memory, and emotional processing (hippocampus, hypothalamus, and amygdala) .
In women, both estrogen and progesterone are crucial for brain cells to make new connections, branch out, and maintain their myelin insulation – key processes for cognition and brain health .
Genetics and age impact the effects of progesterone on mood and even the response to common antidepressants (like SSRIs). In one study, premenopausal women with more active serotonin transporter genes (5-HTTLPR) were more likely to benefit from antidepressants .
Higher sex hormone levels may be needed for antidepressants to achieve the desired effect in women. Due to drops in estrogen and progesterone, menopausal women might gain less benefit from antidepressants – but this is a preliminary finding that needs to be confirmed in large studies .
6) May Help with Weight Loss
Men with progesterone levels in the higher end of the normal range are less obese, have lower BMI and smaller waist circumference. Obese women are also more likely to have very low progesterone levels [6, 13].
In hamsters, the combination of progesterone and estrogen (17 beta-estradiol) lowered their fat stores and increased weight loss .
7) May Reduce Blood Pressure
Women often experience high blood pressure after menopause, but the difference to men becomes more apparent only decades after. Women over 65 years of age experience much faster and greater increases in blood pressure than men .
According to studies of over 40k Italian women, the chances of high blood pressure increase 2-fold after menopause, a risk that can be reduced with hormone therapy. Race may also affect it, as being postmenopausal didn’t increase the risk of high blood pressure in a study of 22k Japanese women .
In a study of 270 women, both natural (200 mg/day) and synthetic progesterone lowered blood pressure given to women shortly after the menopause. Neither combination had beneficial effects if given later after the start of menopause, so early interventions may be key .
The combination of synthetic progestin (medroxyprogesterone acetate) and estrogen lowered blood pressure in 12 postmenopausal women .
Estrogen has a much stronger blood-pressure-lowering effect than progesterone. Naturally-produced progesterone can both relax and narrow blood vessels and doesn’t have beneficial effects on blood pressure in postmenopausal women without estrogen .
Even when combined with estrogen, it’s still unclear if hormonal therapy is beneficial for reducing the risk of high blood pressure or if it can even increase it .
One Australian survey study found the opposite. According to a survey of 43k postmenopausal women, those who used hormone therapy were much more likely to have high blood pressure, the risk increasing with the duration of use. One big flaw in this study was not making any distinction between natural and synthetic progesterone or various other factors that can play in .
8) May Protect the Bones
After menopause, women are at much greater risk of osteoporosis. For a long while, it was thought the blame should fall on declining estrogen. But conventional treatment with vitamin D, calcium, and estrogen can only delay but not reverse osteoporosis. Doctors and scientists then turned to progesterone in search of the missing link [27, 28].
Progesterone’s role is estrogen’s subtle partner is maintaining bone health. It collaborates with estrogen to increase slow, long-term (3 – 4 months) activity of bone-building cells .
The effect of synthetic progesterone on bone mineral density is limited and carries the risk of adverse effects. Natural progesterone creams can protect the bones and are relatively free from adverse effects [2+].
In one study, a combination of transdermal progesterone (along with conventional therapy) increased bone density in women with osteoporosis [2+].
In premenopausal women, it’s important to pay attention to various factors that can reduce progesterone and predispose to osteoporosis later on in life. Low progesterone levels can be triggered by everyday stress, poor diet, emotional, social and financial insecurity, and illness. Low levels are also more common in teens and women shortly before menopause .
9) PMS and Spotting
Women who experience intense PMS symptoms may be deficient in progesterone during this menstrual cycle phase. In healthy women, low progesterone worsens PMS mood symptoms such as aggressive behavior and fatigue [1+].
However, taking progesterone pills may not help during PMS. In a review of almost 300 women, progesterone had a very modest effect on PMS symptoms .
Having balanced progesterone levels throughout the different menstrual cycles maintains healthy, regular cycles. High progesterone and other hormonal changes can cause symptoms:
- High progesterone is linked to heavier menstrual bleeding 
- Higher estrogen and LH levels around ovulation and high estrogen and progesterone in the second phase (after ovulation) are common in women who experience spotting midway through their cycle 
10) May Improve Muscle Mass
In a study of 12 postmenopausal women, progesterone increased muscle mass, unlike estrogen. Progesterone also increased the activity of genes that help build muscles (MYOD1) .
In another study, synthetic progestins with estrogens (medroxyprogesterone acetate + estradiol valerate) increased muscle strength in postmenopausal women .
11) May Prevent Unwanted Hair Growth
In a skin-tissue study, natural progesterone blocked the enzyme that causes a buildup of male sex hormones and contributes to unwanted hair growth in women (5-alpha reductase). Blocking this enzyme can lower high testosterone levels. A commonly used synthetic progestin (medroxyprogesterone acetate) had no effect on this enzyme .
12) May Slows Skin Aging
In a study on 40 women (menopausal and postmenopausal), a 2% progesterone cream reduced wrinkles and increased skin elasticity and firmness. Progesterone facial creams may help slow down skin aging in women after the onset of menopause .
13) Progestin-Only Birth Control (the Minipill)
Also known as the “minipill”, progestin-only birth control is an option used by few women, more commonly in their late reproductive years (usually above 40). These pills are a safer option for women at higher risk of vein problems (venous thromboembolism) due to a family history of the disease, diabetes, obesity, smoking, or other factors .
The minipills contain synthetic progestins is doses lower than those in the typical combination (estrogen + progestin) oral contraceptive pills. The minipill should be taken continuously, without the 4 – 7 day breaks women taking combination birth control are advised to make. In a survey of 13k US women, only 0.4% used the minipill [37, 36].
Various synthetic progestins can be used, although studies didn’t find any specific derivatives more effective than another. All can cause side effects, such as irregular bleeding and irregular cycles .
The minipill works by thickening the cervical mucus and thinning the uterus lining, which prevents sperm from reaching the egg. It only partially suppresses ovulation, unlike combination pills .
14) Autoimmune Progesterone Dermatitis
Autoimmune progesterone dermatitis is a very rare condition that affects young women, mostly in their 30s. Women with this condition experience an allergic reaction to normally raised progesterone in the second phase of the menstrual cycle .
The symptoms range from eczema and skin redness to very severe allergic reactions. Given that only a handful of cases have been documented so far, dermatologists and gynecologists are rarely aware of it. A progesterone skin test is needed to diagnose it. In one case, this condition went away completely with oral contraceptives [38, 39].
15) Insulin resistance
High estrogen and progesterone levels in women during the second phase of the menstrual cycle and during normal pregnancy are linked to reduced insulin sensitivity. Tissues can become insensitive to progesterone, triggering progesterone resistance that worsens insulin resistance .
No studies show that natural progesterone will worsen insulin sensitivity in postmenopausal women.
Progesterone Side Effects
Progesterone (Prometrium) pills can cause the following side effects :
- Breast tenderness
- Fluid retention
- Dizziness and drowsiness
- Hot flashes
- Bloating or stomach cramps
- Increased risk for viral infections
Heart Disease Risk
Synthetic progestins are associated with congestive heart failure .
Breast Cancer Risk
Heavy Bleeding or Spotting
High progesterone levels can cause heavy menstrual bleeding or spotting. Synthetic progestins used in the minipill also cause spotting more often than combination birth control pills .
Forms of Progesterone
Natural Progesterone is available in various forms :
- Vaginal gel
- Progesterone shots/injections, sometimes given during pregnancy to prevent early labor
Both natural progesterone and synthetic progestins are combined with estrogen as part of hormonal therapy.
This test measures the amount of progesterone in the blood and is most commonly used to help monitor a woman’s health during pregnancy, diagnose pregnancy complications, determine the cause of infertility, or determine the cause of abnormal uterine bleeding .
If you are a woman, you need to know at what point you are of your menstrual cycle (period) or pregnancy to accurately interpret your results. Progesterone levels normal rise and fall over the course of your cycle. If they are not following this pattern, then you may not be ovulating or have regular periods, which may cause infertility [47, 48].
In men, progesterone is produced at a much lower level than in women. Most men do not normally get their progesterone levels tested unless they are suspected to have an adrenal disease, such as congenital adrenal hyperplasia (CAH). CAH is a group of disorders that limit hormone production in the adrenal glands .
Depending on the menstrual cycle phase:
- First half: 0.02 – 1 ng/mL
- Ovulation-2nd half: 2 – 30 ng/mL
Progesterone levels during pregnancy can widely range. The following are not strict ranges, the normal range will vary between labs and other factors. As a rough guide, during pregnancy progesterone levels can vary between [49, 50, 51]:
- 8 – 48 ng/mL in the first trimester
- 29 – 50 ng/mL in the second trimester
- 99 – 342 in the third trimester
In postmenopausal women and in men, the normal range is : 0 – 1 ng/mL
However, having a high progesterone level does not always indicate health problems . Progesterone levels increase during pregnancy and are even higher in pregnancies that involve multiples (twins, triplets, quadruplets, etc.) .
Very high progesterone can damage the fetus .
High progesterone can be caused by:
High progesterone symptoms
How to lower Progesterone
- Eat more fiber: Fiber intake decreases progesterone levels [60, 61]
- Exercise can also help reduce progesterone 
- Stop smoking 
- Reduce your caffeine intake 
- Increase natural sun exposure or take Vitamin D supplements 
- Reduce stress
In women, progesterone levels can increase and decrease throughout the menstrual cycle, so you should make sure that the levels correlate with your current menstrual cycle phase.
Low progesterone can potentially cause ovulation and fertility problems. Low progesterone can cause:
- Ectopic pregnancy 
- Miscarriage 
- Toxemia (blood toxicity and high blood pressure) in late pregnancy 
Symptoms of low progesterone
- Headaches 
- Bloating 
- Mood swings [67, 68]
- Insomnia 
- Irregular menstrual cycle 
- Depression [67, 68]
- Infertility 
Low progesterone can be caused by:
Irregular Progesterone Levels?
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How to Increase Progesterone (without taking progesterone)
Maintain a healthy body weight: Obesity and excess weight can cause low progesterone; losing weight can help prevent your progesterone levels from becoming low .
The following supplements can also help:
- Vitamin C 
- Arginine 
- Vitamin B6 
- Chaste Tree Berry (Vitex) 
- Green tea 
- Glucosinolates (cruciferous vegetables) will lower estrogen and help detox
What about the “pregnenolone steal” and estrogen dominance?
Unlike some sources claim, stress does not “steal” progesterone. On the contrary, progesterone increases together with the stress hormone cortisol .
The “pregnenolone steal” theory claims that high levels of stress steal pregnenolone to produce more cortisol, reducing the amount available to produce progesterone. All of this is usually explained within the scientifically-unvalidated theory of adrenal fatigue.
Others talk about “estrogen dominance (ED)”, a theory that can be traced to the late John M. Lee, MD. Dr. Lee’s popular books claimed that everything from breast cancer to PMS and osteoporosis is caused by “estrogen dominance secondary to relative insufficiency of progesterone”. The truth is that this is another overly-hyped theory. Estrogen dominance is talked about a lot but researched very little [8, 79].
An increased number of estrogen receptors, exposure to estrogen-like environmental toxins, and more rarely, high estrogen levels have been linked to poor health in some studies. Excessive estrogen increases the risk of cancer of the uterine lining and may contribute to obesity. But no studies support that estrogen can simply steal pregnenolone from progesterone in all cases [80, 81, 13].
Sex hormones undergo complex changes, especially in women who experience cyclical changes each month. It’s quite unlikely that these biochemical pathways can be deduced to an exclusive theory like estrogen dominance [8, 79].
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