It is important to find out if penis development is abnormal or an individual difference within the normal range? If the penises are slightly small, do they interfere with a normal sex life? That is, can they make the wife get pleasure? The human penis and the body height, fat and thin, the size of the features and so on there are numerous differences, the length varies, the thickness is not uniform. Domestic Shi Chengli has measured the penis size of 1412 healthy Chinese male youths and the erect length of 126 healthy men. The results showed that the longest length at normality was 14.5 cm, the shortest 4 cm, and the average 8.375 cm; the circumference was 12 cm at maximum, 4.5 cm at minimum, and 8.3 cm at average. The longest length at erection was 16 cm, the shortest 9 cm, and the average 12 cm; the maximum circumference at erection was 14 cm, the minimum 8 cm, and the average 10.75 cm. The penile length of 1000 normal adult men investigated by Liu Guozhen et al. was: the range of length in normality was 4.9-8.6 cm, with an average of 6.55 cm, the longest 10.6 cm and the shortest 3.7 cm. Wu Weicheng et al. measured the penis of 2547 male college students aged 16-40 years, and the mean length was 7.43 cm and the mean circumference was 8.17 cm; the mean penile draft length was 13.34 cm, which was similar to the calculated erectile length of 13.08 cm, so the draft length was considered to be representative of the post-erectile length. It can be seen that there are some differences in the measurements of different authors, and the results are also influenced by region and ethnicity. In addition, the length of the penis is not constant in the same person under normal conditions, such as stress, cold, or severe fatigue can cause the penis to shorten. In addition, the method of measurement itself also varies greatly, so it is difficult to judge whether the penis is normal from the length alone. Therefore, the above figures should only be used as a reference and should never be used as a hard comparison of how your length is. Clinicians are also never willing to judge whether the penis is normal by its length. As long as you can have normal intercourse and complete the task of having children is normal. Otherwise this family would have been eliminated long ago. To further explain the reasons for a large or small penis, let’s still review the process of penis occurrence and development together. For the sake of narrative convenience, let’s divide it into four stages: (1) the 10th-12th weeks of gestation, the penis is just differentiated and only 3.5 mm long, when the role is played by testosterone produced under the action of hCG secreted by the placenta. (2) In the middle and second 6 months of pregnancy, the penis grows rapidly and is already 2.5-3.5 cm long at birth, when the fetal pituitary gland begins to secrete the gonadotropins LH and FSH. (3) After birth and until puberty (around 7 years old), the penis grows slowly, which is due to the slow development of the hypothalamus and pituitary gland, and low testosterone levels. (4) After puberty begins, the pituitary gland and testosterone secretion is vigorous, and the penis grows rapidly, reaching adult levels in only about 5 years, growing and thickening. When the level of sex hormones is significantly reduced in old age or after surgical debulking, the penis can degenerate secondary. If secondary impotence stops after many years of sexual contact, it may also cause pathological degeneration, which is not a matter of using in and out as it is generally called, but a consequence of degenerative changes in smooth muscle fibers. In short, the differentiation and development of the penis depends on the level of testosterone in the body. If the testosterone production is insufficient during the 6th-9th months of pregnancy, the penis will develop at a lower than normal rate and will be smaller at birth. So, what is considered a really small penis? The penis is considered to be abnormally developed when it is shorter than 2.5 cm before puberty and shorter than 5 cm after puberty, and when it is abnormally developed and has no erectile function; especially when the secondary sexual characteristics are poorly developed, sexually dysfunctional, non-fertility and no sperm. Causes of true micropenis include: (1) Hypogonadotropic hypogonadism originating in the testes, when the hypothalamus and pituitary gland are normal and able to issue strong commands, but the testes are diseased and unable to carry out the orders to produce sex hormones and sperm. (2) Hypogonadotropic hypogonadism, this is when the hypothalamus and pituitary gland are diseased and unable to send down commands to secrete testosterone. (3) Partial anti-androgen syndrome, in which the penis is insensitive to androgens and the patient has normal testosterone levels but abnormal secondary sexual characteristics and may even have hypospadias. (4) Idiopathic micropenis, the cause of which is still unknown. There is no need to worry at all about this physiological difference of normal penis size, as for the problem of female sexual satisfaction and sexual harmony between the two parties is mainly caused by factors such as poor sexual knowledge and sexual skills, and has nothing to do with penis size. By the way, it is important to measure the length of the penis, one is to measure the weak state, and the other is to measure the change in the erect state. When measuring the room temperature should be about 25 ° C, to be calm and appropriate rest, with the hand to lift the penis flat, with one end of the hard ruler slightly hard against the pubic symphysis, as far as possible to compress the subcutaneous fat layer, the other end of the penis glans urethral orifice as a reference, the number read out is the length of the penis under normal conditions. The circumference of the penis is then measured with a dipstick at the cadre of the penis 1 cm from the coronal rim. Since patients are nervous or uncomfortable with the office environment, they are mostly unable to have an erection in front of the doctor, so the length of penile traction is often used instead of the erect length.