What are the effects of drugs in pregnancy?

Once you take the at-home pregnancy test and realize that your life is about to change, you may have several questions about what is best for the health of you and your baby.

Although your friends and family will likely all have an opinion about what it means to be healthy during pregnancy, avoiding substances like alcohol, nicotine, marijuana, and illicit drugs from the beginning can make the biggest impact on your baby’s future.

The Developing Brain

At birth, the human brain weights approximately 800g, which is more than half of the weight of an adult brain. During embryonic development, the neural tube creates cells that go on to form neurons, the building blocks of the central nervous system (brain and spinal cord). At just 10 weeks after conception, all of the major structures of the brain and spinal cord are recognizable.

During pregnancy the brain is growing very rapidly through processes that involve cell growth, planned cell death and connections between cells. Due to this rapid development, any interference with normal brain development can have a significant impact on physical growth, behavior and cognition, including intelligence and language skills. 

Brain development occurs by cell growth and pruning, a process by which unused cells are shed (or, planned cell death). Brain development also occurs by connection between cells, which creates the development of neural pathways called myelination. Myelination occurs as the baby or child learns, has experiences and bonds with loved ones. 

After birth, brain weight continues to increase to about 1200g at 6 years old, eventually reaching adult weight of 1500g. Brain size due to the number of neurons created accounts for some portion of intelligence. A growing body of research is also linking intelligence to major neural pathways (connections) that are strong and efficient.

Alcohol, Substance Use & Other Risk Factors

The precise nature of fetal growth means that any interference on the size or effectiveness of the brain can have permanent consequences to the child. That is why pregnant women have so many recommendations around food, supplements and medications, and are instructed to abstain from alcohol, nicotine and illicit drug use. 

“The largest body of literature we have currently is around alcohol use during pregnancy and how it affects a child’s growth, neurocognitive development and social-emotional functioning,” said Lindsey Felix, PhD, with Samaritan Neuropsychology.

She reports that a growing body of literature is showing that using cocaine, marijuana and opiates has long term negative consequences, though this is harder to study since gathering reliable information about illicit drug use during pregnancy is challenging.

“Measuring the precise effects of a substance used during pregnancy on a child is difficult since children who are exposed to one substance are often exposed to multiple substances,” said Felix.

Further, she notes that women who use substances during pregnancy often have other risk factors including low socioeconomic status, poor living conditions, poor prenatal care, and their own cognitive, emotional or behavioral problems. These all contribute to neurocognitive and psychological outcomes in their children.

Marijuana & CBD

In Oregon, access to marijuana for recreational use makes it easier than ever for women to use without thinking about the affect it may be having on an unborn baby.

Products containing the cannabis compound CBD from the hemp plant, a cousin of the marijuana plant, are also readily available in stores and online. CBD does not give the “high” feeling associated with marijuana. Additionally, since CBD is a sold as a supplement and is unregulated, there is no way of knowing how much you are actually getting in a dose or if the product has been contaminated with other substances.

“Although there is not yet extensive research on CBD, the effects of marijuana use on a developing fetus are well documented,” said Felix. “Children with a history of prenatal marijuana exposure are at-risk for problems with attentional regulation, visual spatial abilities, and disruptive behavior.” 

Marijuana and CBD, she concludes, should be avoided during pregnancy. 

Long Term Effects For Children

The severity of consequences for the child can depend on how much the mother uses and at what time during pregnancy. Each substance reacts differently in the mother’s body and can affect the baby in different ways, but outcomes run the gamut of affecting intelligence, attention, higher-level executive functions like problem-solving, and language, as well as academic achievement, emotional functioning, behavior regulation, and the child’s own future drug use.

According to Felix, exposure to tobacco/nicotine during pregnancy has been linked to later behavior problems, including ADHD. Marijuana exposure in utero can affect attention, visual perceptual abilities, and behavior problems, including delinquent behavior. Prenatal alcohol exposure is linked to poor physical growth, lower intelligence, attention problems, and academic underachievement. Cocaine exposure during pregnancy has been associated with lower intelligence, and impairments in attention, language, and executive functions, as well as emotional and behavioral problems. Opioid use during pregnancy has been linked to problems with attention, memory, and behavior (including hyperactivity). 

Effective Early Intervention Strategies

As a baby grows physically, intellectually, and socially, a delay in any area may signal a problem. The factors that help determine success start at conception, according to Felix. It is important that pregnant women avoid use of alcohol, illicit drugs, and tobacco/nicotine in order to provide their baby with optimal growing conditions. 

After a child is born, it is important that they are provided with love, a secure connection with their caregivers, and a home free of violence, illicit drugs, and nicotine/tobacco. This sort of loving environment can help mitigate negative effects of prenatal substance exposure.   

Early Intervention Services like speech therapy or physical therapy can address any delays a child may be demonstrating. For school-aged children who are having difficulty with schoolwork or paying attention in class, taking advantage of academic accommodations or special education services at school can be a big benefit, says Felix.

An evaluation by a school specialist or a mental health professional can help develop a plan for learning and behavior at school and home. Felix notes that some combination of classroom tools used by the teacher and parenting tools used at home are the most beneficial. A child’s plan may also include medication.

“For any child, a nurturing home life is going to have as big of an impact on positive development as a genetic predisposition,” said Felix. “Parents who are also tuned in to when their kids need extra help at school are giving their kids the best chance possible to succeed.”

Do you wonder if your child is progressing as they should? Learn more about getting an evaluation at Samaritan Neuropsychology.

Get help with a substance use disorder or tobacco addiction.

When you’re pregnant, taking drugs can seriously affect you and your baby’s health. Sometimes this can be lifelong.

Having a baby can be a positive reason to make changes to your life.

The effect on your baby

Taking drugs (including tobacco and alcohol) when you’re pregnant, even in small quantities, can put your baby’s health at serious risk. It increases the risk they'll be stillborn or will die in the first few weeks and months of life. 

These are difficult things to imagine happening but are real risks if you take drugs.

Your baby's also more likely to:

• be born early
• be underweight
• have feeding and breathing problems
• get infections
• have problems with their development and growth

These can all have life long consequences.

More about smoking in pregnancy and drinking alcohol in pregnancy

Prescribed medicines

You should also speak to your GP, midwife or a drug support service if you’re regularly taking prescribed medicines. Stopping your medication suddenly could be harmful for you and your baby.

More about medicines in pregnancy

Neonatal abstinence syndrome (NAS)

Some prescribed or illegal drugs that can cause physical dependency can pass through the placenta and be absorbed by your baby.

Following delivery your baby may show signs of physical withdrawal known as Neonatal Abstinence Syndrome.

Some of these babies may need specialist care after birth and medical treatment to help them withdraw.

If you have any questions about NAS you should speak to your midwife.

Getting support

If you’re taking drugs and you want to stop or cut down, you can get help and support from your midwife and your local drug support service.

If you’re taking any drugs, talk to your midwife or GP as soon as you can after finding out you’re pregnant.

They can help you understand the risks and support you to cut down or stop taking drugs.

Drug support services

Support services are there to help you. They’re private and confidential and the staff who work there will listen to you and support you without judging you.

If you’re already being supported by a specialist drug support service, tell them that you’re pregnant as soon as you know.

Find a drug support service in your area

If someone close to you is taking drugs

Your partner, your baby’s dad or someone close to you might be the one taking drugs. That can be worrying and make the future feel uncertain, stressful and challenging.

Your partner or anyone close to you can also get direct support.

Talk to your midwife or GP if you’re worried about someone or think they need help.

Scottish Families Affected by Alcohol and Drugs (SFAD) can help you understand more about substance use in the family, provide ways to stay safe, and offer advice and support on how to keep others in your household well.

You can contact SFAD by:

• email
• phone 08080 101011, Monday to Friday, 9am to 11pm (a call-back service is available on weekends)

Translations and alternative formats of this information are available from Public Health Scotland.