What Is Low Progesterone

Low progesterone can cause a wide range of problems for you and your body. This article will explore low progesterone and potential issues that could accompany it.

Progesterone, the lesser discussed sex hormone when compared to its family members, oestrogen and testosterone, has many important functions in numerous processes, from bone formation to the menstrual cycle.

This article will discuss the biological processes affected by low progesterone levels. Before going on to look at the causes, diagnosis, and treatment of low progesterone. 

Overview

Progesterone is a hormone that acts as a chemical messenger in the body. They are produced by specialised cells and released into the blood so that they can communicate with their target tissues and organs. More specifically, progesterone is a sex hormone; it is made in the gonads (the ovaries or testes) and the adrenal gland. In women or individuals assigned female at birth (AFAB), progesterone has many targets in the tissues of the reproductive system. It also plays a role in bone formation, breast development, breastfeeding, the central nervous system, and the cardiovascular system. In men, or people assigned male at birth (AMAB), progesterone is present in much lower amounts but is still important as a precursor for testosterone, an antagonist to oestrogen and a facilitator in sperm development.^{1, 2}

Progesterone and the Menstrual Cycle: The menstrual cycle has four phases: menstruation (your period), the follicular phase, ovulation, and the luteal phase.3 Once the egg is released from your ovary at the point of ovulation, the ovarian follicle in which the egg develops forms a structure named the corpus luteum. The corpus luteum secretes progesterone, which prepares your uterus (womb) for the event that, at ovulation, the egg is fertilised by a sperm. Progesterone directs your uterine lining (endometrium) to thicken, which helps the implantation and growth of the early embryo. If the egg is not fertilised, the corpus luteum will cease progesterone secretion. In the absence of progesterone, the endometrial lining will shed, and menstruation occurs.⁴

Progesterone and Pregnancy: If, following ovulation, the egg is fertilised by a sperm, the corpus luteum continues to produce progesterone in order to maintain the lining of the uterus up to the ninth week of pregnancy. The placenta takes over the role of progesterone production and, therefore, the maintenance of pregnancy, whilst the corpus luteum degenerates at week twelve. In pregnancy, progesterone is not just important for the maintenance of the uterus lining, it also prevents premature contractions of the muscles in the uterus wall to stop preterm labour. In addition, progesterone helps regulate the production of immune cells inside the uterus to protect the developing embryo.^{1, 4}

If you have lower than normal progesterone levels, many of your body’s biological systems can become unbalanced. Low progesterone can have direct effects, such as causing your menstrual cycle to become irregular, making it harder to become pregnant or maintain the pregnancy once fertilisation has occurred. Low progesterone can also have indirect effects. In your body, hormones operate as a complex, interlinked network. Therefore, if one hormone level changes, this can cause all the hormones in the network to become imbalanced.¹ 

Causes of low progesterone

Progesterone levels naturally fluctuate during your menstrual cycle and decline as you go through the perimenopause and enter menopause. However, there are other reasons why you might test positive for low progesterone. The most common of these reasons are:

Anovulation: An anovulatory cycle is a menstrual cycle where ovulation (egg release) fails to occur. In a cycle where ovulation does occur, the empty follicle left behind (referred to as the corpus luteum) produces progesterone. If egg release does not happen, there is no corpus luteum to make progesterone.⁵

Polycystic Ovary Syndrome (PCOS): PCOS is a hormonal imbalance, an endocrine disorder. The endocrine system is formed of the glands and organs that produce and release hormones into the bloodstream.⁶ There is no definitive cause for PCOS, and there are many different clinical features. It can cause anovulatory cycles and amenorrhea (missed periods).⁷  

Hypothyroidism: Hypothyroidism, or an underactive thyroid, is also an endocrine disorder. If the thyroid is not producing enough hormones to sufficiently regulate the endocrine system, it becomes harder for your body to produce high enough levels of other hormones, including progesterone.⁸

Hyperprolactinemia: Hyperprolactinemia is the overproduction of prolactin by your body. Prolactin is a hormone produced by the pituitary gland to control lactation. However, it also decreases the production of the precursors to the sex hormones. Therefore, the more prolactin released, the less progesterone can be produced.⁹

Low Cholesterol: The common precursor, the raw material, of a steroid hormone is cholesterol. Without enough of the precursor molecule, your body cannot produce a sufficient amount of progesterone.¹

Over-Exercising or Extreme Dieting: In a state of low energy availability, your body cannot produce sufficient amounts of all the sex hormones, including progesterone.¹⁰ 

Signs and symptoms of low progesterone

Low progesterone can affect your body in many different ways. In women (or AFAB), symptoms of low progesterone that you might notice include:¹¹

• Irregular menstrual cycles
• Headaches or migraines
• Mood changes
• Anxiety
• Depression
• Difficulty conceiving

You may also experience symptoms of high oestrogen (another steroid reproductive hormone) as it is balanced by progesterone. These are:^{12, 13}

• Weight gain
• Depression
• Gallbladder issues
• Low libido (sex drive)

If you are pregnant, the signs of low progesterone are:¹

• Spotting
• Ectopic pregnancy
• Preterm labour
• Miscarriage

If you are a man (or AMAB), despite requiring less progesterone, you can still experience the effects of low progesterone. Symptoms you may feel include:¹⁴

• Depression
• Low libido
• Erectile dysfunction
• Loss of muscle mass
• Fatigue

These symptoms can all manifest from a range of different conditions. If you do experience any of these symptoms, report them to your doctor so they can get to the root cause. Once the cause is established, they can treat your condition appropriately to reduce those symptoms. 

Management and treatment for low progesterone

You may not feel any effects of having low progesterone. However, if you do, your healthcare practitioner can recommend a range of treatment options tailored to your individual needs. If you are trying to get pregnant, progesterone can be prescribed to ensure the lining of your uterus thickens and is maintained throughout the embryo’s development in the womb. For menopause-related symptoms, a more holistic approach will be used, known as hormone replacement therapy (HRT), where both oestrogen and progesterone are given.^{15, 16} Progesterone and HRT can be administered in any of the following forms:¹⁷

1. Creams or gels that can be used topically
2. Cream or gel suppositories that are inserted into the vagina
3. Oral pills
4. Skin patches
5. An implant may be used to administer HRT in some circumstances.

There are risks and side effects associated with both progesterone and HRT treatments. Your healthcare provider will discuss these with you prior to prescribing them. The most common side effects associated with progesterone treatments include:¹⁷

• Headaches
• Menstrual cycle irregularities
• Breast pain
• Drowsiness
• Gastrointestinal discomfort

There are also some conditions that might mean your healthcare practitioner might advise against hormone therapy, such as a history of blood clots, breast cancer or genital cancer.¹⁷ If you have low progesterone and are experiencing its effects, you can work with your healthcare provider to establish the best method of treatment for you. Once you have found what treatment works, your symptoms are likely to resolve. Over time, you may need to adjust your treatment in line with your current lifestyle or to reduce any side effects of the treatments you currently take. This is completely normal; your healthcare provider is there to support you to find the best treatment for you and your goals, whether that be pregnancy or just feeling more yourself. 

Diagnosis

To diagnose you with low progesterone, your healthcare provider will refer you for a blood test that will measure the amount of progesterone in your blood. The amount of progesterone in your blood varies depending on your gender, where you are in your menstrual cycle, if you are pregnant, or approaching menopause. Your results will be reviewed with this in mind in order to give you the right diagnosis.¹⁸ 

FAQs

How can I prevent low progesterone?

The causes of low progesterone are often not preventable. However, you can protect against low progesterone levels caused by low energy availability by ensuring you balance exercise and fuel intake. 

How common is low progesterone

It is difficult to say how common low progesterone is, there are no studies that try to put a number on it. It is important that if you are experiencing any of the symptoms of low progesterone or have one of the underlying causes of low progesterone, you get your hormone levels checked. 

Who is at risk of low progesterone?

If you are a woman, or AFAB, as you get older your reproductive hormone levels, including progesterone, will fall. If you have been diagnosed with another condition that affects the balance of hormones in your body, you may also be at risk of developing low progesterone. 

What can I expect if I have low progesterone?

Low progesterone can cause a range of issues in men (or  AMAB), and women (or AFAB). However, with help from the treatments recommended by your healthcare practitioner, your quality of life will not change. Although, it may take a while to work out what treatment works best for you, and this may change over time.  

When should I see a doctor?

You should contact your doctor if you have any of the symptoms of low progesterone, such as your menstrual cycle becoming irregular, spotting during pregnancy or between periods, headaches/migraines, or changes in your mood. There are many other reasons for these kinds of symptoms. Your doctor will go through your medical history and refer you for a series of tests that will help them deduce the exact cause of your symptoms. If you are diagnosed with low progesterone and experience side effects from the treatments that are difficult to cope with in day-to-day life, it is important that you go back to your doctor. They may be able to change the intensity, or method of hormone therapy that would work better for your body. 

Summary

Progesterone plays many important roles across several body systems. It is especially important in the reproductive system for the regulation of the menstrual cycle and maintenance of pregnancy. If you have low levels of progesterone, you may experience a range of symptoms depending on your gender, if you are pregnant, or if you are entering menopause. Once your healthcare provider has diagnosed low progesterone through a blood test, there are a number of treatment options available to reduce your symptoms.