Slow sperm is one of the most common alterations of male fertility, but it does not necessarily mean infertility. These are its causes, how it is diagnosed and what options exist.<\/p>\n
Some diagnoses raise more questions than answers. One of them comes when, after a semen analysis, the specialist explains that the sperm have low motility or, put more colloquially, that they are “slow sperm” and have difficulty reaching the egg. From that moment on, inevitable questions arise for the couple: does it mean it will be impossible to have children? Is there any treatment? What can be done to improve sperm motility?<\/p>\n
Having slow sperm can reduce the chances of pregnancy, but it does not mean pregnancy is impossible. In addition to motility, fertility depends on multiple factors such as the number and shape of sperm, the woman’s reproductive health and other circumstances of the couple.<\/p>\n
Infertility affects approximately one in six people of reproductive age during their lifetime, and the male factor is involved, alone or together with the female factor, in about half of cases.1<\/sup><\/a>,<\/sup>2<\/sup><\/a> In this context, sperm motility has become one of the most studied parameters because of its essential role in fertilisation.<\/p>\n For a natural pregnancy to occur, sperm must travel through the female reproductive tract to reach and fertilise the egg. It is not enough for them to be present in sufficient numbers; they also need to move effectively.<\/p>\n When a significant proportion of sperm cannot move with the necessary speed or efficiency, we speak of low sperm motility. The medical term is asthenozoospermia, also known as low sperm motility<\/a>, an alteration diagnosed with a semen analysis and one of the most common causes of male-factor infertility.<\/p>\n The severity of the alteration is assessed according to the percentage of motile sperm observed in the semen analysis and should always be interpreted by a specialist together with the rest of the semen parameters. If the percentage of immotile sperm is between 60% and 75%, asthenozoospermia is considered mild or moderate; above that range it is considered severe, with a poorer prognosis.3<\/sup><\/a> Nevertheless, an abnormal semen analysis is not the same as a diagnosis of sterility.<\/p>\n Although semen analysis is the reference test for assessing semen quality, a single test is not always enough to establish a definitive diagnosis, as fever, some infections, certain medicines or even an inappropriate period of abstinence before the test can temporarily change the results. For this reason, the guidelines of the Spanish Fertility Society (SEF<\/a>) and the WHO recommend repeating the analysis when there is any clinical doubt.<\/p>\n The causes of low sperm motility are very diverse and, in some patients, no specific origin is found. That is why specialists recommend interpreting the semen analysis together with the medical history and other factors such as:<\/p>\n The most common clinical causes that alter spermatogenesis and slow down sperm include varicocele (abnormal dilation of the veins of the spermatic cord), active infections of the reproductive tract, hormonal imbalances (such as low testosterone levels), obstructions in the seminal ducts or genetic abnormalities affecting the structure of the sperm flagellum.<\/p>\n The cellular environment of the testicles is extremely vulnerable. Lifestyle habits such as smoking (which alters sperm DNA), excessive alcohol consumption, a sedentary lifestyle, obesity or type 2 diabetes significantly increase oxidative stress in the seminal fluid, impairing motility.<\/p>\n Likewise, continuous occupational exposure to pesticides, heavy metals or sources of intense, prolonged heat on the testicular area (saunas, very tight clothing) can reduce sperm production and vitality. When no specific medical or external cause can be identified, the condition is classified as idiopathic asthenozoospermia.<\/p>\n Once a definitive diagnosis has been reached, the management of low sperm motility should be personalised and aimed at correcting the underlying medical cause<\/a>: surgery for varicocele or obstructions, antibiotics if there is an infection or hormonal treatment if there is an imbalance. When the problem is related to lifestyle, changing habits can also help improve semen parameters. In other cases, when the alteration persists or makes conception difficult, assisted reproduction techniques such as artificial insemination or in vitro fertilisation may be considered, always according to the characteristics of each couple.<\/p>\n In addition to the treatments currently available, there are innovative lines of research looking for new alternatives for men with mild or moderate alterations of sperm motility. In this field, PROKREA<\/a> is investigating a pentoxifylline vaginal gel (PKB171) to increase sperm motility at the moment of fertilisation.<\/p>\n In short, although hearing that sperm are “slow” usually causes concern, that result is only the beginning of the study of reduced sperm motility. Identifying the cause, interpreting the semen analysis correctly and choosing the most suitable strategy allows many couples to achieve a pregnancy.<\/p>\n Are you trying to conceive and have you been diagnosed with low motility?<\/strong><\/p>\n The EASY clinical study, authorised by the Spanish Agency of Medicines and Medical Devices (AEMPS), is investigating a local, non-invasive alternative for couples with a possible mild male factor who have been trying to conceive for between 6 and 24 months.<\/p>\nWhat does it mean to have low sperm motility?<\/h2>\n
Degrees of severity of asthenozoospermia<\/h3>\n
Why are sperm slow? Main causes<\/h2>\n
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Medical and anatomical factors<\/h3>\n
Lifestyle and environmental factors<\/h3>\n
Slow sperm: solutions and available treatments<\/h2>\n
New lines of scientific research: Prokrea’s vaginal gel<\/h2>\n