Researchers say more than 80% of autism risk involves genetic factors, but the environment also plays a part. If a child has susceptible genes, exposure to the right chemical or drug could spark a chain reaction that leads to autism.

Avoiding triggers during pregnancy is critical. A child’s brain develops rapidly in utero, and the damage done here could lead to autistic changes.

In this guide, we’ll discuss common substances linked to autism development, including the following:

  • Antidepressants
  • Acetaminophen
  • Asthma medications
  • Valproic acid
  • Painkillers and illicit drugs
  • Toxic chemicals

Use this information to talk with your doctor about what you should avoid during pregnancy to lower your child’s autism risk.

When Does Autism Develop?

Autism prevention begins before your baby is born. While autism research is ongoing, most experts agree that the disorder begins within the womb.

The drugs and chemicals a woman takes into her body can change the environment for her growing baby. Sometimes, those shifts can cause autism changes.

Experts say exposure to toxic chemicals during pregnancy can spark gene mutations. Those changes can alter the way the brain develops in a fetus. The damage can’t be corrected after birth, and it persists throughout the child’s life.

During pregnancy, a child’s brain produces 250,000 neurons a minute. Anything that alters those connections can change your baby’s brain in ways that persist. You may not notice any adjustments until long after your baby is born, but the damage is there. When your child fails to talk or walk later in life, you’ll suspect that something happened.

Researchers say MRI scans of children as young as 1 year old can detect autism alterations. Doctors don’t typically diagnose the disorder until much later when a child has grown and changed, but the problem exists long before signs appear.

When we talk about avoiding toxic drugs and chemicals, we should focus on a mom’s health during pregnancy. By the time a child is born, it might be too late to change the child’s developing brain. The choices a mom makes while she carries her child could help to lower the odds of autism.

Antidepressants During Pregnancy

For many women, pregnancy is a time of intense excitement and anticipation. For others, raging hormones and a rising sense of responsibility intertwine and lead to dread and worries. Sometimes, women develop depression during pregnancy, and sometimes, women with lifelong depression enter pregnancy.

Depression is a serious, but treatable, disorder. Doctors use a wide variety of medications to help their patients. Some of these medications have been linked to autism.

In a European study, researchers examined published studies containing these keywords:

  • Selective serotonin reuptake inhibitors (or its known acronym, SSRI)
  • Autism spectrum disorder (or its known acronym, ASD)
  • Pregnancy
  • Childhood
  • Children
  • Neurodevelopment

They examined all the data from these studies, and they found a strong association between SSRIs and autism risk.

Women taking these drugs grew concerned. Should they switch to another medication? The answer isn’t easy. To change medications, women must:

  • Talk with their doctors. They must disclose how they feel now, how long they’ve taken SSRIs, and how they felt before the treatment began.
  • Taper down their dosage. Stopping SSRIs abruptly can lead to a return of severe depression. A tapered approach to stopping use works better.
  • Start a new medication. Doctors must choose a comparable drug, and they must start it at a reasonable dose.
  • Adjust the dose, or try again. Some women get immediate relief from a new medication. Others must experiment before they find the right fit that offers effective results with few side effects.

Moving through this process takes weeks or even months. Women already pregnant may not have time to complete each step before the baby arrives. Some researchers aren’t sure panic is warranted.

A 2015 Canadian study also linked antidepressants and autism. In this study, less than 1% of the 150,000 babies included in the study developed autism by age 6 or 7.

The risk is so low, and the known dangers of untreated depression are so high, that some experts felt women should continue to take the drugs that work for them. Doing so is the best way to help a baby, they suggest. Leaving depression untreated leads to underweight babies, and in some cases, it sparks maternal suicide attempts.

Also, research done on antidepressants is observational. That means teams:

  • Pick two groups. One group uses antidepressants, and the other doesn’t.
  • Watch them closely. They keep notes on each group of people throughout the study period.
  • Make assumptions. If changes between the two groups appear, they are attributed to the use of antidepressants.

Studies like this don’t prove causality. It’s possible the depression, and not the drug, caused autism, but that fact often gets blurred and lost in translation. Until studies with twins are performed, researchers just don’t know how antidepressants could help or harm developing babies.

Acetaminophen During Pregnancy

Pop open any medicine cabinet in America, and you’re likely to see bottles of acetaminophen tucked amid the bandages, prescription medications, and toothpaste. When we have aches and pains, we reach for acetaminophen to soothe the discomfort. Some say pregnant women should think twice before taking these pills.

In 2019, researchers examined the cord blood of women taking acetaminophen during pregnancy. It’s an interesting technique, as acetaminophen metabolizes quickly, so detecting the substance in the blood isn’t easy. But seeing it helped the researchers understand how much of the element moves from mom to baby. They found that higher exposure leads to higher autism risks.

Dose-dependent relationships like this suggest that risks and use go hand in hand. The more a woman uses, the more potential harm she causes her baby.

However, the researchers encourage caution. Their study does not prove that acetaminophen causes autism. They’re not sure how the drug changes brain development. They’d like other teams to conduct more studies, so those complex questions get valid answers.

The U.S. Food and Drug Administration (FDA) monitors studies like this, and when concerns arise, the agency releases rules to help consumers make smart decisions. For now, they say uncontrolled pain can cause significant problems in pregnant women, including:

  • Anxiety
  • Depression
  • High blood pressure

Women and their doctors should weigh the risks and benefits of using drugs like acetaminophen during pregnancy, the FDA says. For now, the agency doesn’t ban the use of this substance during pregnancy due to autism risks.

Asthma Drugs During Pregnancy

Women breathe for two during pregnancy. Each breath they take fuels their bodies with oxygen, but their babies also rely on those breaths for their health and development.

Asthma sparks lung inflammation, which makes breathing difficult. People with asthma may wheeze or gasp for air without medication management. Sometimes, the drugs women use to control asthma symptoms can pass through the umbilical cord to developing babies, and that comes with autism concerns.

In 2016, researchers from Drexel University determined that children born to women who took B2AR drugs for asthma during pregnancy were more likely to have autism than their peers.

Other experts found problems with this study, including:

  • Data collection. Researchers looked at prescriptions filled, not the actual medication used.
  • Observational issues. This study looked for connections without specifying a cause and effect.
  • Levels of asthma severity. Women who fill these prescriptions may have more significant symptoms than those who don’t. That could lead to lower fetal oxygen rates, which could also spark autism.
  • Environmental factors. Researchers didn’t include data about where the women lived or what other autism triggers were routine for them. A lot of information is then missing.

Additional studies, including one published in 2019, found associations between asthma severity and autism, independent of medication use. Research like this suggests that women with asthma need to use working medications to protect their babies. They should also talk with their doctors about what substance might work best.

Valproic Acid During Pregnancy

Seizures are electrical storms within the brain, and they’re life-threatening for pregnant women and the babies they carry. Valproic acid is an anti-seizure medication, and it could be part of a woman’s treatment plan. However, this drug could cause an increase in autism risks.

In a large study conducted in 2015, researchers found risks of autism were significantly increased when women took valproic acid during pregnancy. These results have been replicated in studies performed with animals.

For now, it’s best for women with seizure disorders to work with their doctors on treatment plans before they get pregnant. Another solution could help them reduce their risk of episodes while protecting their child’s developing brain.

Drugs During Pregnancy

Women have access to all sorts of substances, including some that are legal and others that aren’t, and many can cross from a mother’s body to her baby. Two substances like this concern autism researchers: cocaine and opioids.

  • Cocaine: In a small study of 70 children exposed to cocaine during pregnancy, 11.4% developed autism. In addition, 94% of these children had some form of language development delay. Cocaine readily passes from mother to child, and the drug works by altering brain chemistry. Based on studies like this, it seems the drug changes a child’s brain in a negative way.
  • Opioids: These strong medications help to quell pain in people with chronic conditions, such as back injuries or foot problems. In a study, women who got prescriptions for opioids just before they got pregnant were 2.5 times more likely to have a child with autism than mothers who didn’t take opioids. Researchers didn’t examine people who took these drugs without a prescription.

Women should always talk to their doctors before taking either of these drugs. If women are addicted to opioids, they should ask for help before they get pregnant, so their bodies can heal before pregnancy starts.

For women who unexpectedly get pregnant while struggling with opioid abuse, there are solutions. Consult a doctor immediately. It can be dangerous to mother and baby to suddenly stop taking opioids if the body is physically dependent on them. Doctors can supervise the withdrawal process, if appropriate, to ensure everyone stays safe.

Pregnant women who are struggling with drug abuse need other forms of help besides medical care. Addiction treatment is needed to ensure the well-being of the mother and her child.

Environmental Hazards During Pregnancy

Many of the toxins women should avoid come in pill or needle form. However, some persist in the air we breathe and the water we drink.

Autism Speaks says women should steer clear of these environmental risks during pregnancy:

  • Mercury
  • Lead
  • Pesticides
  • Endocrine-disrupting chemicals, including phthalates

For some women, reducing risk is as easy as moving. Moving from an apartment that is filled with old paint and next to a field could reduce a mother’s exposure to both pesticides and lead.

For other women, a chat with their doctor makes sense. You may face risks you’re unaware of, and a doctor can help you determine smart steps to take.

While autism can’t be wholly prevented, there are steps pregnant women and their families can take to lower the risk.


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