What is a micropenis and do I have one?


The micropenis is statistically found in 0.6 percent of the population, making it a rare feature. This term is most often used when all other structures of the genitalia, including the scrotum, testes, and perineum, are "normal." During intrauterine development, abnormalities can occur as a result of genetic aberration or be caused by hormonal abnormalities.

Laura Porter / Get Medication Information

Micropenis symptoms

At birth, a penis less than 0.75 inches long is considered a micropenis. In an adult, a flaccid penis less than 2.75 inches long is considered a micropenis. An erect penis is considered a micropenis if it is less than 5 inches long .


The micropenis develops during pregnancy. Often this will be the only physiological abnormality seen during pregnancy .

One of the possible reasons for this is the low production of human chorionic gonadotropin (hCG) in early pregnancy. It is a hormone that stimulates the production of testosterone in the developing testes .

After 14 weeks, the growth of the penis is influenced by another hormone known as luteinizing hormone (LH), which also stimulates the production of testosterone in the so-called Leydig cells of the testes. If the production of one or both of these hormones in the fetus is difficult, it can affect the length of the baby's penis .

Genetics can also play a role. Although there is no single gene that causes micropenis, the condition is commonly associated with chromosomal abnormalities such as androgen insensitivity syndrome (AIS), Klinefelter syndrome, Turner syndrome, and Down syndrome .

There is also evidence that estrogen-based fertility drugs, such as diethylstilbestrol (DES), can reduce penis size when taken early in pregnancy. pregnancy can cause micropenis and other genital abnormalities in male babies .


In newborns, it is very important that the doctor correctly measures the baby's penis when diagnosing the micropenis. Unlike flaccid penis length (FPL), in which the penis is parallel to the rule, the extended penis length (SPL) should be used, as it correlates more closely with the length of the erect penis in boys and men .

To do this, the doctor must firmly press a rigid ruler against the pubis at a right angle. The penis is then held laterally with a gauge just below the glans (glans) and stretched to its maximum length without pain. New syringe-shaped instruments are also available that can be slid over the penis and suctioned to its fully extended length .

The correct definition of the micropenis in babies is essential, as it allows for potentially effective treatment. The doctor should also investigate conditions commonly associated with the micropenis, including problems with the pituitary gland or hypothalamus .

Definition of micropenis

While an SPL of less than 1.9 centimeters is a diagnostic feature of a micropenis in full-term babies, for older boys and men, a micropenis is characterized by a penis length of 2.5 standard deviations (SD) lower than average for this age .

As a guideline, the Johns Hopkins University Harriet Lane Handbook defines the micropenis as follows:

  • 6 to 12 months: less than 2.3 cm (0.9 inches)
  • 1-2 years: less than 2.6 cm (1.02 inch)
  • 2 to 3 years: less than 2.9 cm (1.14 in.)
  • 3-4 years: less than 3.3 cm (1.3 inches)
  • 4-5 years: less than 3.5 cm (1.38 inch)
  • 5-6 years: less than 3.8 cm (1.5 inches)
  • 6-7 years: less than 3.9 cm (1.54 inches)
  • 7-8 years: less than 3.7 cm (1.46 inches)
  • 8-9 years: less than 3.8 cm (1.5 inches)
  • 9-10 years: less than 3.8 cm (1.5 inches)
  • 10-11 years: less than 3.7 cm (1.46 inches)
  • Adult: less than 9.3 cm (3.66 inches)

Differences in average penis size after age 7 are due to differences in the development of boys as they approach puberty. At the time of puberty, it becomes much more difficult to define the micropenis with only centimeters; Algorithmic calculations are required before puberty is complete.

Differential diagnosis

While the clinical definition of micropenis appears to offer a comprehensive diagnostic plan, this is not always the case. This is especially true for children over the age of 8.

In fact, most prepubertal boys brought in by their parents due to underdevelopment of the penis rarely have a micropenis. In most cases, the boy suffers from delayed puberty, obesity (hides the length of the penis due to excessive amounts of pubic fat) or simply has a larger body than a normal penis.

In such cases, it is more appropriate to use the term "invisible penis". It can be secondary to congenital conditions such as penoscrotal membrane (in which the scrotum rises over the bottom of the penis, creating a blurred connection between them) and megapreduction (in which the foreskin cannot retract or swell abnormally) .

Watch out

Micropenis treatment depends on children and adults. Since the genitals of babies and young boys are still developing, testosterone treatment can aid penis growth, often significantly. Surgical options, although limited, can be investigated in boys and men whose penises are at their maximum height.

Depending on the treatment plan, the medical team may include a pediatrician , urologist, endocrinologist , geneticist, or psychologist.

Testosterone therapy

Micropenis can be treated in infants and children with three monthly injections of intramuscular (IM) testosterone. Research has shown that one or two cycles of three testosterone injections (25 to 50 milligrams) at four week intervals can increase a boy's penis size to the normal range for his age .

For a male child with a micropenis, circumcision should be postponed until testosterone therapy is completed. Generally speaking, therapy is most effective in children younger than 3 years old, but may be beneficial for children younger than 8 years old.

Sex change

In the past, young boys with micropenis often underwent gender reassignment surgery , more in response to general cultural discomfort due to their small penis size than actual medical need .

This practice has largely declined today, with most experts questioning its wisdom, given the potential benefits of testosterone therapy, the need for lifelong male-to-female hormone therapy later in life, and the lack of individual consent.

If carried out, gender reassignment is generally considered at a later age, when the child can make an informed decision and undergo a thorough psychological evaluation.

Penis enlargement surgery

Some men with a micropenis, with varying degrees of success, will choose to undergo penis enlargement surgery (phalloplasty). One of those operations, called ligament support release, involves separating the ligament that supports the penis during erection .

This allows the penis to be positioned at an obtuse rather than acute angle, creating a longer sensation. Potential risks include nerve damage, loss of penis sensation, erectile dysfunction, and retraction of the penis if scar tissue forms at the incision site .

Other forms of phalloplasty, such as flap surgery (skin grafts from another part of the body), are used less frequently because they carry a significant risk of complications and can interfere with sexual function.

Other methods, such as silicone implants (prostheses), synthetic dermal fillers, and subcutaneous fat injections, are more likely to increase the girth of the penis rather than the length. Even if an increase in length is achieved, it will only affect the flaccid length and not the straight length, which will remain the same.

There are also commercially available penis pumps and stretchers that have not shown consistent results in increasing penis length. If accomplished, they tend to be humble at best. These devices are intended for men with erectile dysfunction; this is a separate issue.

Front facing

In practical terms, the micropenis can make urination difficult, making it difficult to direct the jet. Many men simply compensate for this by sitting on the toilet while urinating.


More importantly, a penis length of less than 2 inches is associated with a lower chance of conception. Also, some men with a micropenis will have a low sperm count as a result of an underlying pituitary disease. In such cases, assisted reproductive techniques are available that greatly increase the chances of conception.


While there are treatments that can increase penis size, the reality is that some people have a smaller penis than usual. While some people assume it will cause psychological harm, these beliefs reflect our cultural attitudes toward penis size more than a person's individual experience.

In fact, long-term studies have shown that men with micropenis are no different from men with an average or above average penis size .


The micropenis has not been shown to affect male libido, sexual function, sexual satisfaction, the ability to achieve an erection, or the ability to develop mutually beneficial sex .

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