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Causes of Autism Spectrum Disorder

30 September 2025

People have been trying to figure out what causes ASD since the 1940s, when the first studies on the disorder were published and people with the disorder were diagnosed. The answer to this question is still unknown, and there is no one cause of ASD. Most people, though, believe that ASD is a complicated disorder that is caused by a mix of genetic (some of which are passed down through families) and environmental factors. There are also conditions known to raise the risk, such as

  • Parents who are older, especially the father.
  • Frequent pregnancies, less than a year apart.
  • Males are 4 times more likely to develop ASD than females.
  • Having another child with ASD is more likely after having a child with ASD.

Risk factors during pregnancy

Some people believe that pregnancy is one of the most important times for both the fetus and the child's brain development. This is why it has been suggested that the environment inside the uterus can affect how the brain develops normally. A rise in the number of people with ASD has also been linked to a number of different factors, but as of now, no direct link has been shown between them.

Some of these factors are listed below:

  • Thyroid gland problems in the mother
  • There are many problems that can happen during pregnancy, but some of the most common ones are premature birth, low birth weight, preeclampsia, gestational diabetes, and more.
  • Not enough minerals and vitamins while pregnant.
  • Infections with viruses and bacteria while pregnant.
  • Alcohol consumption, drug use and taking of certain medications during pregnancy.
  • By using the hormone oxytocin to start labor.
  • In-vitro fertilization (people have different thoughts on this).

Since the 1940s, with the beginning of research on ASD, the publication of studies on the subject, and the diagnosis of various cases of ASD, focus has been placed on the causes of the disorder. The response to this question remains unknown to this day and no specific cause of ASD can be indicated but the prevalent belief is that ASD is a complex disorder that is affected by a combination of genetic (some of which are hereditary) and environmental factors.

The article below will emphasize the unique risk factors that can affect the birth of a child with ASD, disprove incorrect myths about autism, and, above all, increase awareness of the disorder while minimizing exposure to influential factors. If you are parents or are about to become parents in the future, this article is especially for you.

Risk factors

Although it is currently impossible to pinpoint a specific cause of ASD, specific circumstances are known to increase the risk, including:

  • Older parents, particularly the father.
  • Frequent pregnancies, less than a year apart.
  • Males are 4 times more likely to develop ASD than females.
  • The birth of a child diagnosed with ASD increases the risk of ASD in ensuing children. Siblings of a child with ASD face a 5% to 20% risk of being diagnosed with ASD (approximately 20% among males and 7%–9% among females).

Risk factors during pregnancy

Pregnancy is considered one of the most critical periods in fetal brain development and later brain development in the child. For this reason, the intrauterine environment has been suggested to affect normal brain development Furthermore, several factors have been found to be associated with an increase in the rate of ASD, but no causal relationship between them has yet been proven.

Below are some of these factors:

  • Dysfunction of the mother’s thyroid gland: even mild hypothyroidism may increase the risk of ASD.
  • Complications of pregnancy, with emphasis on premature birth (premature infants), low birth weight, preeclampsia, gestational diabetes, placental abruption, delay in intrauterine fetal growth as well as disruption in oxygen supply during birth.
  • Low levels of vitamins and minerals during pregnancy: failure to take or not taking a high enough dose of folic acid, which is critical to the development of the central nervous system; low levels of vitamin D; or iron-deficiency anemia.
  • Viral and bacterial infections during pregnancy: prenatal vaccination against viruses (influenza, chicken pox, German measles) may reduce the risk of illness during pregnancy.
  • Alcohol consumption and taking of certain medications: completely abstain from alcohol consumption, smoking, and drug use during pregnancy. Discuss with your physician the safety of chronic medication during pregnancy.
  • Induction of labor by the hormone oxytocin: several studies have been published in recent years on a correlation between induction of labor by the hormone oxytocin (the hormone responsible for, inter alia, uterine contractions) and increased risk of ASD among newborns delivered in said manner. A possible explanation may be attributed to the fact that the hormone affects social functioning in people, and administering high doses of the hormone at birth may affect the internal secretion mechanisms in the newborn's brain.
  • In-vitro fertilization (IVF): some studies attribute the procedure to an increased risk of developing ASD, but the medical world is divided on this opinion.

Debunking Myths about ASD

Various misconceptions and myths have taken root in society over the years. These perceptions, which often stem from a lack of information or misinformation, affect not only how society treats people with ASD but also their quality of life and equality of opportunity. Debunking these myths and understanding the complex reality of autism is critical towards creating a more inclusive and enabling society.

Below are some of the common myths that it is important to disprove:

There is a connection between vaccines and ASD

Wrong!

International experts and the results of studies conducted on the subject have definitively revealed no connection between vaccines (including the measles, mumps, and rubella MMR vaccine) and the development of ASD.

ASD is a disease

Wrong!

ASD is a neurological condition and hence cannot be ‘cured’ but rather provides understanding, treatment, and support for the unique needs of the individual with ASD.

There is a link between ASD and intellectual capacity and talent

Wrong!

Autism is not an intellectual disability and is not related to the individual's intellectual or cognitive capacity. Some people with ASD demonstrate strong intellectual abilities, and there are those who demonstrate less. In addition, it does not directly affect the talent or creative ability of the individual.

People with autism do not understand emotions

Wrong!

Reality has proven that many people with ASD experience a deep emotional world, can understand a wide range of emotions, and develop significant emotional bonds. The difference is that they may process emotional information differently, which can occasionally lead to difficulties in identifying or expressing emotions. Additionally, they may not understand social cues, but this does not affect their ability to understand emotions.

Finally, it is important to remember that behind all the studies, data, and statistics, there are people—children and adults—living with ASD. Everyone is a world unto themselves, with unique strengths, challenges, and dreams. As we continue to broaden our understanding, break down stigmas, and promote social awareness, we can create a more inclusive world for people with disabilities. At the same time, progress in research also brings with it hope for additional support and understanding, for equal opportunities, and a life full of meaning and self-realization for every person, regardless of their place on the spectrum.

Assisted in the preparation of the article: Ido Michaeli-Assor, speech pathologist, Autism Department at the Ministry of Health and director of the "Shavim" Center in Jerusalem.