Mental retardation belongs to the category of mental illness in the International Classification of Diseases (ICD), but the disease is closely associated with the education sector, civil affairs, pediatrics, etc. Therefore there are terms such as mental retardation, intellectual disability, and mental retardation. I will give a brief introduction on the relationship between mental retardation and maternal pregnancy, the determination of IQ, and the assessment of intellectual disability, which are of concern to everyone. Mental retardation (MR) refers to a group of syndromes that begin before the age of 18 years with incomplete or impaired mental development and are characterized by significant mental retardation and social adjustment deficits. According to the American Association of Mental Retardation (AAMR), there are at least 350 causes of mental retardation. Biological, psychosocial and other factors may lead to developmental delays in brain function or structural damage to brain tissue, and with recent advances in medical science, the cause can be identified in some cases, but in many cases the cause has not yet been identified. The World Health Organization (WHO) classifies the causes of mental retardation into ten major categories: infections and poisoning; trauma and physical factors; metabolic disorders or malnutrition; brain diseases (postnatal); prenatal factors and diseases due to unknown causes; chromosomal abnormalities; immature children; severe mental disorders; psychosocial deprivation; other and non-specific causes. So, what should mothers pay attention to before and after pregnancy to try to avoid or reduce the appearance of mental retardation? Genetic factors: A large number of domestic and international studies have shown that genetic factors are very evident in MR patients. Abnormalities in chromosome number and structure, as well as monogenic and polygenic inheritance, are very common in MR. For example, trisomy 21, which is often referred to as congenital stupidity, is an abnormality in chromosome number. Fragile X syndrome, phenylketonuria, and tuberous sclerosis, which cause mental retardation, are also associated with genetic factors. Therefore, couples with a genetic predisposition should make the necessary preparations before marriage, and it is advisable to consult in advance whether they can become pregnant. Maternal Pregnancy Injury: In recent years, there has been a trend toward a decrease in patients with MR, which, in addition to genetic factors, is related to a decrease in maternal injury during pregnancy. Studies have shown that maternal infections (viruses, spirochetes, toxoplasmosis) during the fetal period, especially viral infections in the first trimester, are highly likely to cause abnormalities in fetal development. The common ones are rubella virus, herpes simplex virus, cytomegalovirus, etc. Contamination of food and water, especially some harmful food additives in food nowadays, can have a significant effect on the fetus. And it is also proven that drugs taken by pregnant women cause malformations and mental retardation in babies. These drugs have the greatest impact in the first trimester, so in principle it is generally not easy to take drugs during pregnancy unless it is life-threatening. Psychiatric drugs, in general, have a greater impact on the fetus, so if you must take them, please consult a senior psychiatrist or related specialist. Excessive smoking and alcohol abuse can affect the development of the baby, which can lead to mental retardation. In addition, advanced gestational age, poor nutrition, and emotional abnormalities are also risk factors. Many of the patients with MR seen today are due to brain disorders after birth. On the one hand, this is due to failure to receive timely treatment, and on the other hand, it is due to inadequate medical care and irrational use of drugs. Nowadays, with the emphasis on disease and the abundance of material conditions, such phenomena are less common. The IQ test is a scientific test of intelligence, which mainly tests a person’s thinking ability, learning ability and ability to adapt to the environment. Modern psychology has different views on intelligence. The so-called intelligence refers to the ability of human beings to learn and adapt to the environment. Intelligence includes the ability to observe, remember, imagine, think, and so on. The level of intelligence directly affects a person’s success in society. The level of intelligence is expressed by IQ, which is between 90 and 109 for normal people; 110 to 119 is the upper middle level; 120 to 139 is the excellent level; 140 or more is the very excellent level; while 80 to 89 is the lower middle level; 70 to 79 is the critical state level; and below 69 is the intellectual deficiency. Generally speaking, people with higher IQ are more capable of learning, but there is not necessarily an exact positive correlation between the two. Because IQ also includes the ability to adapt socially, some people who have strong learning ability do not have strong social adaptation ability. Therefore, the diagnosis of mental retardation should not be based only on IQ, but also on the social adaptation level, learning ability and work ability of the “patient”. Our hospital is currently able to provide IQ tests for children and Wechsler tests for adults. Lastly, intellectual disability is defined as a person’s intelligence that is significantly lower than that of the general population and shows impaired adaptive behavior. According to the World Health Organization (WHO) and the American Association on Mental Retardation (AAMD), intellectual disabilities are classified according to their intelligence quotient (IQ) and socially adaptive behaviors. Grade I intellectual disability: i.e., very severe intellectual disability. IQ of 20 or 25 or less. The adaptive behavior is extremely poor; the face is obviously dull; the whole life needs to be taken care of by others; the motor-sensory function is extremely poor, if trained, only in the lower limbs, hand and jaw movement is responsive. (Note: The former IQ value is measured by the Stanford-Binet scale and the latter is measured by the Wechsler scale). Grade 2 intellectual disability: severe intellectual disability with an IQ value between 20-25 or 25-40. Poor adaptive behavior; difficulty in taking care of oneself even after training; poor motor and language development, and poor interaction with others. Grade 3 intellectual disability: i.e. moderate intellectual disability. iQ value between 35-50 or 40-55. Adaptive behavior is incomplete; practical skills are incomplete, such as being able to partially take care of oneself and do simple household chores; having a preliminary general knowledge of health and safety, but very poor reading and calculation skills; poor ability to discriminate the surrounding environment, and being able to interact with others in a simple way. Grade 4 intellectual disability: i.e. mild intellectual disability. IQ value is between 50-70 or 55-75. Adaptive behavior is below the level of the general population; has considerable practical skills, such as being able to take care of oneself and undertake general household chores or work, but lacks skill and creativity; can generally adapt to society with guidance; can acquire some reading and calculation skills with special education; has good discrimination ability of the surrounding environment. Can interact with people more appropriately.