Low Progesterone: What Symptoms Are Typical?

• Progesterone is produced by the corpus luteum after ovulation and is important for implantation.¹
• Progesterone balances estrogen. Without enough of it, the effects of estrogen dominate.⁶
• With low progesterone, the second half of the cycle is often shorter or progesterone levels are low.²
• A second half of the cycle shorter than 12 days is considered short.²
• Progesterone raises your basal body temperature, so your temperature chart shows how long the second half of your cycle lasts.^3,4

After ovulation, the follicle turns into the corpus luteum. It produces progesterone, which prepares the uterine lining for implantation and the early development of an embryo.¹ If you don't get pregnant, progesterone levels drop and your period starts. Progesterone also raises your basal body temperature slightly. That's why a temperature chart shows a high-temperature phase after ovulation.^3,4

Other medical terms for a luteal phase defect are luteal phase deficiency or corpus luteum insufficiency. It means a shortened second half of the cycle, low progesterone levels in the second half of the cycle, or a uterine lining that doesn't respond well enough to progesterone.^1,2

A second half of the cycle shorter than 12 days is considered short.²

In the first half of the cycle, estrogen builds up the uterine lining. After ovulation, progesterone slows this buildup and prepares the lining for possible implantation.^1,6

If ovulation doesn't happen, no corpus luteum forms and no progesterone is produced. The uterine lining is then exposed to estrogen alone for longer. This can lead to excessive buildup of the lining and to irregular bleeding.⁶ With a luteal phase defect, progesterone is also missing as a counterbalance in the second half of the cycle.²

Important: This is not about too much estrogen, but about too little progesterone in relation to it. If your cycles often have no ovulation or your bleeding is very irregular, have it checked by a doctor.⁶

• Short high-temperature phase: The time between ovulation and your next period is repeatedly shorter than usual.^1,2
• Progesterone levels: Doctors measure progesterone in the blood two to three times in the middle of the second half of the cycle.² You'll often hear "test on day 21." But that only works for a 28-day cycle. Your temperature chart shows you when the middle of your high-temperature phase is.^3,4
• What about saliva tests? Some doctors, such as Dr. Annelie Scheuernstuhl, measure progesterone in saliva. Their reasoning: a blood test measures protein-bound and free hormone together, while saliva mainly reflects the free, active hormone. The test is also simple and can be done at home at the right time. Women who still have a cycle usually test on cycle day 22, in the middle of the high-temperature phase. Your temperature chart shows you when that is for you (see above). Women without a cycle, for example after menopause, can test on any day. Menopause societies are critical of this approach: lab methods for saliva tests are not standardized, and results depend on things like how much you've had to drink or eat.^15,25 If you use a progesterone cream, saliva levels are often many times higher than blood levels. The saliva result then says little about how much progesterone actually reaches your body.^26,27
• Trying to conceive: In fertility testing, a luteal phase defect is considered a possible cause of reduced fertility.²

Symptoms such as breast tenderness, water retention, mood swings, or headaches before your period are often linked to an imbalance between progesterone and estrogen. If you notice these symptoms regularly in the second half of your cycle, take a look at your temperature chart: how long does your high-temperature phase last?

• Perimenopause: In the years before the last period, ovulation often starts to change early on. The second half of the cycle gets shorter and progesterone levels drop, while estradiol fluctuates widely and is even higher on average. This imbalance can contribute to heavier bleeding.¹² Cycles without any ovulation become more common.¹¹ On your temperature chart, this shows up as a shorter high-temperature phase or as a cycle without a temperature rise.⁴
• Bones: Estradiol slows bone breakdown, and progesterone supports bone formation. In lab studies, progesterone stimulates bone-forming cells. Women with disrupted ovulation during their reproductive years lose bone density. During perimenopause, women lose bone mass faster than after menopause, and researchers believe a lack of progesterone contributes to this.¹³
• After menopause: Progesterone can still matter after menopause. The ovaries no longer make it¹¹, but in a study of postmenopausal women, body-identical progesterone relieved hot flashes and night sweats significantly better than a placebo.¹⁴ Body-identical progesterone comes in different forms, including creams that some OB-GYNs prescribe as custom compounded formulations. In hormone therapy, progesterone matters for more than protecting the uterine lining: it is the natural counterbalance to estrogen⁶, has a calming effect in the brain^7,8, and can relieve hot flashes and night sweats.¹⁴ If you take estrogen and have a uterus, you also need it to protect the uterine lining.¹⁵ The form can make a difference too: in a French study, estrogen through the skin, as a gel or patch, was not linked to a higher risk of blood clots, while estrogen pills were. Body-identical progesterone was not linked to blood clots in that study either.²⁴ For bone protection, progesterone alone was not enough in studies after menopause.¹³ Whether hormone therapy is right for you, and in which form and dose, is best discussed with your OB-GYN or healthcare provider.
• Progesterone is not the same as a progestin: Body-identical progesterone has exactly the same chemical structure as the progesterone your body makes. Synthetic progestins, such as those in birth control pills or many older hormone therapies, are chemically modified and work differently. Think of it like a lock and key: body-identical progesterone fits your body's receptors exactly. Synthetic progestins only fit approximately and can also bind to other receptors. The terms are often mixed up. For hormone therapy, body-identical progesterone is considered the option with the more favorable benefit-risk profile.¹⁵

Everyone knows about hot flashes. But almost no one links these 5 signs to perimenopause.

For many women, perimenopause starts in their mid-40s, sometimes earlier, and can last several years.¹¹ Estrogen fluctuates widely, and progesterone declines.¹² Hormone receptors aren't only found in the uterus and breasts, but also in the brain⁸, bones¹³, and eyes²¹, for example. That's why the transition often shows up in places few people would think of. Dr. Annelie Scheuernstuhl, a physician in Starnberg, Germany, describes it this way: "During this time, most women get a feeling that 'something in my body is different.' But the symptoms don't match the commonly cited classic menopause symptoms." She often sees this as a relative progesterone deficiency that can be noticeable from the early 40s.²³

These 5 signs are often misread:

1. Joint and muscle pain: According to a meta-analysis of more than 5,800 women in perimenopause, about 71 percent are affected.¹⁸
2. Heart palpitations: In a large US study, about half of women in perimenopause and early postmenopause had recurring palpitations.¹⁹ They are often harmless. Still, always have them checked by a doctor.
3. Waking up at night, even without hot flashes, for example at 3 a.m. Waking up at night is the most common sleep problem during the menopause transition, and sleep problems increase up to late perimenopause.²⁰
4. Dry eyes, dry skin, dry mucous membranes: Sex hormones affect the tear and oil glands of the eye, for example.²¹
5. Restlessness or anxiety: The menopause transition can make you more vulnerable to anxiety and low mood, probably partly because of fluctuating estrogen.²² At the same time, levels of calming progesterone decline.^7,12

With symptoms like these, you might first see an orthopedist, a cardiologist, or an eye doctor. Tell them about your cycle, too. Perimenopause isn't just about hot flashes. It affects your whole body.

In the 1940s, American chemist Russell Marker succeeded in making progesterone from diosgenin, a substance found in Mexican yam. In 1944, he produced about three kilograms (about 6.6 pounds) of progesterone from roughly ten metric tons of roots in Mexico and founded the company Syntex.¹⁷ Body-identical progesterone is still made this way today: in a lab from a plant substance, not as a plant extract. In 1953, British physician Katharina Dalton, together with Raymond Greene, coined the term "premenstrual syndrome" and treated her patients with progesterone, among other things.¹⁶

A luteal phase defect is often linked to egg maturation: if the follicle matures unusually quickly or slowly, the corpus luteum may then produce too little progesterone. Thyroid disorders and elevated prolactin levels are also named as causes.² But a luteal phase defect can also occur in healthy women with normal cycles.¹

Your OB-GYN or healthcare provider can find out what's behind it and whether treatment makes sense.

Want to know whether your body is making progesterone in the second half of your cycle? Your temperature chart shows you every month, at home, without a test: if your temperature rises after ovulation and stays up, progesterone is at work.^3,4

Daysy measures your basal body temperature every morning and detects from the temperature rise whether ovulation has happened.⁴ In the DaysyDay app, you can see your chart over many cycles. That way, you can see how long the phase after ovulation lasts and whether it is similar from cycle to cycle.

Daysy does not measure hormones and does not make a diagnosis. If you notice that your high-temperature phase is repeatedly very short, bring your cycle data to your appointment with your OB-GYN or healthcare provider.