With the application of the fifth edition of the WHO semen routine standards, many men of childbearing age often react to the semen test results with the question, “What? I have such a high percentage of abnormal sperm? Can I still have children?” “Will these deformed sperm cause fetal abnormalities?” Based on such questions, I would like to explain “Teratozoospermia” in detail. First of all, what is the definition of deformed spermatozoa? According to the fifth edition of the WHO sperm morphological analysis standards, less than 4% of normal sperm is considered teratozoospermia. Generally speaking, normal spermatozoa are tadpole-like in shape and can be divided into head, neck and tail. However, human spermatozoa can also develop abnormally, and these abnormally developed spermatozoa often appear oddly shaped under the microscope, such as pear-shaped heads, small heads, and double tails (as shown in the figure). It is true that the normal rate determined by the 5th edition of the standard will be lower than that of the 4th edition, precisely because the new edition of the standard is much stricter than the old one, just like students taking an examination, if the questions are very difficult, naturally everyone will score lower. This explains why patients often ask, “My normal rate used to be 50%, but now it’s less than 4%. This explains why patients often ask, “I used to have a 50% normal rate, but now I have less than 4%. So, what are the effects of deformed sperm? Can high sperm malformations cause fetal abnormalities? These deformed sperm usually have some functional defects, they have difficulty breaking the egg barrier and do not allow the egg to be fertilized. Only a small percentage of these sperm can begin the “trek” to the egg, and only the strongest one is able to unite with the egg to form a fertilized egg. Of course, if there are too many deformed sperm, the proportion of normal “fighting” sperm will be significantly reduced and the number of effective sperm will be significantly reduced, thus making the wife’s chances of conceiving less likely, so it seems that sperm deformities only reduce the probability of pregnancy. Some studies have found that an increase in sperm malformation alone does not lead to an increase in fetal malformation, but the highest incidence of fetal malformation occurs during the first trimester of a woman’s pregnancy. During this period, if a pregnant woman takes harmful drugs (antibiotics, hormones, neurotoxic drugs, etc.), is exposed to toxic environment (smoking, pesticides, radiation), or is infected with certain pathogens such as viruses, the development of fetal organs will be directly endangered, resulting in fetal malformation or delayed development. In this way, even if the sperm malformation rate is too high, the fetus will not necessarily be malformed. However, a small percentage of patients with teratozoospermia also have high rates of sperm DNA fragmentation and chromosomal abnormalities, which may result in higher rates of miscarriage and fetal abnormalities, and should be screened promptly. How is teratozoospermia caused? Long-term bad habits such as staying up late, smoking, alcohol abuse, or working in a high temperature, toxic and radioactive environment for a long time, or with reproductive gland infections such as epididymitis, orchitis or vesiculitis, or with varicocele may cause teratozoospermia. Is there any trick to improve teratozoospermia? The key to improving teratozoospermia is to firstly correct bad habits such as staying up late, smoking, etc.; secondly, improve or avoid harmful working environment such as high temperature, toxic and radiation exposure, etc.; furthermore, strengthen antioxidant therapy including high dose of Vit C and Vit E, supplementation of trace elements such as zinc and selenium, etc.; finally, actively treat primary diseases such as gonadal infection and varicocele. Even if some patients with aberrant spermatozoa have difficulty in reducing the sperm malformation rate and natural fertility through the above treatments, assisted reproductive technology can help patients achieve their wish of having a healthy baby.