Maternal mental health could influence whether a child is born autistic, but genes may also play a role.

Autism is a neurodevelopmental difference that seems to begin before birth.

Although the traits of autism spectrum disorder don’t appear until the toddler years, the months in utero may set the stage for the interaction between genes and environment.

The mental health of the pregnant parent may be one of the factors leading to the brain differences in a child.

A pregnant person’s physical state may affect the development of the unborn baby.

For example, gestational diabetes can increase the chance that a baby may also develop diabetes later in life.

This could also apply to mental health and aspects of the baby’s development.

Depression and antidepressants

Some mental health conditions are treated with medications, but when it comes to developmental differences in babies, this isn’t necessarily a factor.

A 2018 study — including 194,494 mother-child pairs — revealed that the chance of autism in the children was influenced more by the mother’s depression symptoms during pregnancy than by their use of antidepressants.

The study showed that both treated and untreated depression during pregnancy increased the chance of a baby having autism. However, the children of women who used antidepressants for reasons other than to treat depression were not as likely to develop autism.

In general, there’s not much evidence that taking antidepressants during pregnancy impacts the baby in any way.

Stress

Depression isn’t the only mental health factor that can influence pregnancy outcomes.

High levels of stress during pregnancy may also be connected to autism in children. This connection appears to have the most impact when the parent experiences stress between weeks 25 and 28 of pregnancy.

Research from 2018 indicates that the same connection may be true when it comes to maternal stress levels and the fetus’s brain development.

Abusive partner

In the same line as chronic stress, experiencing abusive behavior from a romantic partner before and during pregnancy has also been connected to a higher chance of autism in children, according to a nurses’ health study from 2016.

The study results suggest that when a woman is exposed to partner abuse in the two years before giving birth, including during pregnancy, the baby has a higher chance of developing autism later.

Substance use disorder

Substance use disorder in the parents can also play a role in the development of autism in a child, according to the findings of a 2018 hospital-based study with children between 6 and 14 years of age.

The study found that when a fetus was exposed to substances such as opioids and illicit drugs, children were more likely to develop symptoms of attention deficit hyperactive disorder (ADHD) and autism years after birth.

Heritability refers to a measure of how genes account for differences in personality traits among people.

The highest heritability score is 1.0, which means a trait comes 100% from genes. The lowest score is 0.0, which indicates that genes aren’t involved at all.

The current heritability estimate for autism spectrum disorder is 0.83. This means that the development of autism is largely attributed to genetic differences.

However, it’s not just genes that determine how a baby’s brain develops. Other factors like the environment can influence how a person’s genes are expressed.

Epigenetics refers to how your behavior and environment influence how your genes work.

In other words, you could have the gene for a given trait, but it doesn’t mean that you’ll always develop the trait. This depends, in part, on the environment you grow up in, your temperament, and some of your experiences.

Research from 2020 shows that a combination of maternal genes and environmental factors during pregnancy influence how likely a baby is to develop autism.

There are several types of prenatal screening, but none is used to test for autism.

Some of the tests used during pregnancy to track fetus development include:

  • Blood tests. Blood drawn from the pregnant parent can signal the chance of certain conditions in the baby, like Down syndrome or spina bifida.
  • Ultrasound. An ultrasound is a noninvasive test that uses sound to create images which can reveal fetal development.
  • Fetal genetic testing. This type of testing can check the baby’s genes for certain differences, like extra chromosomes.

A 2022 study examined archived pregnancy ultrasounds from 659 children, some with autism. Results revealed differences in development in 29.3% of kids who were later identified as autistic.

By comparison, the identified differences occurred less often in their allistic (non-autistic) siblings (15.9%).

This suggests the future possibility of establishing biomarkers that can be identified via ultrasound during pregnancy. These could help predict the chance of a baby developing autism later on in life.

Autism is a neurodevelopmental difference that may have a strong genetic component as well as environmental influences.

The mental health of the pregnant parent can influence how a baby’s brain develops when in the uterus. Other aspects like early experiences may also impact how a child develops after that.