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What is a Micropenis?

<p>What is a Micropenis?</p>
Dr. Constance Odom, MD Picture of Dr. Constance Odom, MD

Medically reviewed by

Written by our editorial team.

Last Edited 7 min read

Many men compare the size of their penis to society's standards, leaving them with preconceived notions and a whirlwind of emotion if the size isn't deemed satisfactory. This causes them to assume they have some sort of abnormality or a condition like a micropenis. However, the condition is not as common as one may think. In fact, statistics show that just 0.6% of men are affected worldwide, and in the US, approximately 1.5 in 10,000 newborns are born with micropenises.

A microphallus or micropenis is a rare medical condition where hormonal or genetic problems cause the penis to be below-average size. Medical professionals often diagnose the condition during the newborn or early childhood stage. 

This deviation in size often doesn't present any issues, and the micropenis can function normally. They can pee, engage in sex and achieve an erection as long as no underlying medical conditions are present. Below we expand on this condition, its causes, solutions, and more:

Micropenis Sizes and Stats 

The definition of a 'big' or 'small' penis hasn't been firmly plotted or nailed down as we humans aren't copy-and-paste organisms, but of course, the concept of size has been researched extensively, be it for a superficial or medical reason. Nevertheless, it gives us a clearer picture when dealing with a condition like micropenis, which predominantly deals with size variations.

Statistics help us recognize normal and micropenis lengths, making way for successful diagnosis at any stage of life, especially if the issue wasn't caught at birth. Measuring the penis at birth or during infancy might sound a little unnecessary, but it is actually quite important to determine normal development and ensure that conditions such as this are not present.

Penis growth typically becomes rapid during puberty between the ages of 9 and 14, when male characteristics start to really show themselves. The development typically lasts 3 to 4 years, during which the penis will increase in both length and thickness. The rate at which this happens varies from one individual to another. 

Below is evidence from a study that outlined the size of an average penis compared to those who have been diagnosed with a micropenis. 


Average penis length (stretched)

Micropenis (stretched)

Newborn- 30 weeks 



Newborn- 34 weeks 



Full-term newborn 



0 to 5 months



6 to 12 months 



1 to 2 years 



2 to 3 years



3 to 4 years 



4 to 5 years 



5 to 6 years 



6 to 7 years 



7 to 8 years 



8 to 9 years 



9 to 10 years 



10 to 11 years






Causes of a Micropenis 

As mentioned earlier, micropenis is a condition caused by a hormonal imbalance. This imbalance is commonly present at birth while the baby develops in the womb. The hormone affected is typically testosterone—levels of the hormone are too low, preventing the baby from developing normally. 

Fetal testosterone deficiency occurs when a male baby does not create enough testosterone or when the mother does not have enough of the human chorionic gonadotrophin (hCG) hormone, which is vital in producing fetal testosterone. 

In rare cases, testosterone levels may appear normal, but the body does not respond to the hormone properly. This is a genetic disorder called androgen insensitivity. Any of these hormonal issues can contribute to the improper development of the penis, leading to micropenis. 

An NCBI study evaluated two boys with a micropenis with normal androgen (male sex hormone) levels and no evidence of other penile abnormalities. After analysis, researchers found mutations in the androgen receptor (AR), which caused androgen insensitivity. The study proved that androgen insensitivity could cause micropenis without other effects. 

In general, male newborns experience a sudden rise in testosterone at around 0 to 3 months. This is an important time frame for healthy penile growth. If the processes are disrupted by these hormonal problems, then a baby may develop the condition micropenis shortly after birth—infancy. 

It should be noted that a micropenis cannot develop as you age and is almost always present at birth or infancy, sometimes with or without hormonal-related deficiencies. In some cases, the reason behind the condition remains unclear, and most professionals pin it on family history.

More Causes of Micropenis Explained 

Early issues with testosterone sit at the forefront of the cause list of this condition. Although it's the most common cause of the condition, it's not the only one. Let's look at some other causes below:

  • Kallmann Syndrome- This inherited hormonal disorder completely delays or stops puberty. The condition occurs due to the underdevelopment of certain neurons that communicate with the brain, resulting in no production or release of vital hormones. Research showed that 50% of males with Kallmann Syndrome have a micropenis.

  • Prader-Willi syndrome- Prader-Willi is a rare genetic disorder that causes gaps or missing components on chromosome 15. This affects a part of the brain called the hypothalamus, which is responsible for hormone production. A study noted that males with the syndrome typically have a micropenis, paired with other penile abnormalities. 

  • Laurence-Moon syndrome- This is a rare genetic disorder resulting in complex problems with various body parts. It is triggered by one or more abnormal genes affecting hormone levels. 

  • Growth hormone deficiencies- Low growth hormone (GH) levels contribute to fluctuating or low levels of other hormones in the body, like testosterone. A study showed that GH deficiencies are usually the primary cause of micropenis due to their effect on testosterone. 

  • Abnormal chromosomes- This refers to any alteration in the nature or number of one or multiple chromosomes, which affects various processes in the body. A PubMed study showed that chromosome abnormality, especially on a sex chromosome, could cause micropenis. 

Other research has also linked the occurrence of micropenis to pesticide and endocrine-disrupting chemicals (EDCs) exposure during pregnancy. A study done in Brazil showed a high rate of micropenis in their population due to high environmental and occupational exposure to EDCs before and during pregnancy. This proves that this is an important risk factor to be considered in the malformation of the penis, leading to micropenis. 

Over the years, evidence has also shown that increased exposure to estrogen could cause negative effects on male sexual development. This can be a possible cause of low fetal testosterone, resulting in micropenis. 

Micropenis Diagnosis

The primary symptom of a micropenis is its small size, which depends on age. Adults with a micropenis will have an average erect penis length of 3.67" or less. The testicle and other genitalia are still average sizes, but it is still possible to have small/underdeveloped testicles with a micropenis. 

If an individual suspects that they have a micropenis, they must visit the doctor, who will take accurate measurements and make the correct diagnosis. However, micropenis is usually noticed and diagnosed at birth. At birth, doctors typically measure the stretched penis from the pubic bone to the tip (penis head). A micropenis in babies is when the stretched length is 0.75" or less. 

Doctors may also perform the following tests to come to a diagnosis and possible causes:

  • Imaging scans- This includes an MRI or pelvic ultrasound to investigate the surrounding areas of the genitals. 

  • Blood tests- These tests can check hormone levels, which is the leading cause of micropenis. They may also perform genetic tests to determine if the individual has genetic conditions or a sex chromosome abnormality. 

Professionals typically take so many angles to diagnosis because some men can be misdiagnosed with a micropenis based on visual appearance, but in actuality, they are suffering from another condition that causes the penis to appear smaller. Some conditions that may be mistaken for micropenis are:

  • Trapped penis- This is characterized by less penile skin around the genitals. This is usually a complication after surgical procedures.

  • Buried penis- The penis is hidden under the excess skin of the thigh, abdomen, or the scrotum, which is the sac below the penis that holds the testicles. This is usually very apparent in men who have class III obesity, which is a complex disease where a person has a body mass index (BMI) of 40 or higher. 

  • Webbed penis- This occurs when the skin from the scrotum is connected too high on the penis. This causes a web-like appearance when you stretch your penis away from the scrotum. 

Micropenis Treatment Options

There are two possible treatment options for increasing the size of a micropenis. The treatment you opt for ultimately depends on the root cause of the micropenis and professional assessment/recommendation. 

Effective treatment options include:

  • Hormone therapy

Hormonal therapy can be done in several ways—oral tablets, skin patches, or injections. Once the chosen method is administered, the level of the deficient hormone gradually increases in the bloodstream. The hormones then attach to the androgen receptor of the penis and set off a chain of reactions that alters the penile tissue. 

This causes the penile tissue to multiplicate and results in growth. The penis will start growing in size if the penile tissue continues to multiply. This process usually continues for a year and automatically slows down after the penis has grown to a normal size. 

Here are the various types of hormone therapy:

-Testosterone-replacement therapy - This is one of the most common treatment approaches to increase penis size. A study showed that oral testosterone treatment increased penile growth in men with a micropenis. Other evidence showed that topical testosterone applied twice daily produces notable penile growth.

-DHT (dihydrotestosterone) therapy- This is usually for individuals who do not respond to other treatments. A study posted by PubMed stated that topical DHT treatment increased penile growth with micropenis from different causes.

-Human chorionic gonadotropin (hCG) therapy - A study showed that hCG therapy increased the testosterone level in the body, increasing penile length and testicular volume. The results concluded that the therapy is effective in treating micropenis. 

Other types of hormone therapies include growth hormone therapy and IGF-1 (insulin-like growth factor-I) therapy. A clinical report showed that these hormones are important in male sexual development, making them a good treatment option for increasing penis size. 

Hormone therapy is typically used short term and only continued if the penis grows about 0.49" or more in 3 months. This growth confirms that the treatment will work long-term and grow further. Side effects of hormonal treatment may include muscle pain, increased thirst, dry skin, weight loss, and a bitter taste in the mouth. 

  • Penis enlargement surgery

There are three types of penis enlargement procedures; penis girth-increasing surgery, chordee correction, and penis lengthening surgery. This treatment approach is only taken when hormones have not produced any results. 

Penis-lengthening surgery aims to increase the length of the penis. The benefits and lengths may vary between men, but they usually see about 1.5" of gained length. If the pubic area above the penis is overpowering the length of the penis, your doctor will recommend liposuction. 

Side effects from surgery may include nerve damage, infections, reduced sensitivity, and increased difficulty in getting and keeping an erection. Sometimes, the scarring can leave the penis looking shorter than before. This is why surgery is often the last option. Men who have seen growth from hormone therapies are not eligible for any penis surgical procedure. 

Micropenis vs. Sexual Function 

As we mentioned earlier, micropenis does not prevent individuals from getting erections, having orgasms, masturbating, or urinating. However, they may be unable to have penetrative sex. This may cause anxiety and avoidance of sexual activities altogether, which can cause frustration for both the man and his partner. 

Men with micropenis may feel unsatisfied with how their penis looks and assume they cannot satisfy their partner's needs. This is still a looming concern for some men, even after treatment. However, research shows that most men have a healthy, functioning sexual life post-treatment, overthrowing the looming concern of some. 

Penetrative sexual intercourse is only one of the various ways to enjoy sex with your partner. If someone has difficulties with this aspect of sex, it does not have to be an obstacle to receiving and giving sexual pleasure. 

research study showed that a large number of women prefer clitoral stimulation over penetrative stimulation when trying to reach orgasm or maximum levels of satisfaction. This proves that women prefer sexual techniques and other forms of sex, such as oral more than intercourse itself. This provides men with more sexual confidence pre and post-micropenis treatment. 

Professionals also suggest trying the following tips for a pleasurable sexual experience with a micropenis:

  • Be confident. Having the right mindset is one of the most important things in having good sex. If you reduce your anxiety about the appearance of your penis and focus on positive self-talk, you and your partner will have a good sexual experience. 

  • Use toys and props. This doesn't mean you cannot perform well, but it includes different sensations and fun. You can use toys such as dildos, vibrators, and even a strap-on. Adding toys to the bedroom not only increases your partner's sexual pleasure but makes you look super confident. 

  • Understand and communicate with your partner. This will allow you to understand your partner's sexual desires and different ways to please them. It will also increase sexual confidence and build a closer bond with your partner. A study showed that couples were more satisfied with sexual communication and understanding. 

The Take-Away

Although penis length, girth, and size is a touchy subject that can sometimes cause a wave of concern for some, the condition rarely goes undiagnosed or missed at birth. Even if the condition is missed and diagnosed later in life, it is treatable. Hormone therapy is the first treatment approach and almost always produces excellent outcomes. While a full average-sized penis may not be gained, treatment does help you regain control of aspects of your life that were affected by the condition. Talking with your partner and going through therapy can help you overcome performance anxiety and break down the barriers of having a micropenis. 



21 Sources

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This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your physician about the risks and benefits of any treatment. Nu Image Medical may not offer the medications or services mentioned in this article.