What is micropenis?

Micropenis is defined as a penis that has developed normally in terms of structure and appearance, but is smaller than the normal range for an infant. Normally, a full-term newborn boy's penis measures between 2.8 to 4.2 cm long when carefully stretched and measured from the tip to the base of the penis. A penis smaller than 1.9 cm long is usually considered micropenis.


Genital development involves a complex sequence of events that are dictated by chromosomes and hormones. If the body does not produce enough androgens (the hormones that cause male genital development) or if the body does not react fully to the hormones produced, the development of the genitalia will be affected. Micropenis is likely caused by insufficient androgen during fetal development.

Testing and diagnosis

Diagnosis is usually made by physical examination. It is important to have your child diagnosed by a doctor. Many times, the doctor’s evaluation finds that the penis size is very much within the normal range. A penis may appear smaller than average if the child has a large suprapubic fat pad.

Your child will be evaluated by a urologist through our program for Disorders of Sex Development. We will help arrange an evaluation with an endocrinologist (a physician who specializes in hormones) if necessary.


Your child's physician will determine the best treatment. Hormone therapy may be indicated for some children to stimulate penile growth.

Our team includes a psychologist who will help you and your child adjust to this condition over time.

Reviewed by: Division of Urology
Date: June 2011

Next Steps
Mom holding infant daughter

Your Child's Urology Surgery

Find information to help you prepare for your child's upcoming urology surgery at Children's Hospital of Philadelphia.

Boy smiling

Why Choose Us

The Division of Urology at Children’s Hospital of Philadelphia is consistently ranked as one of the top pediatric urology programs in the nation.