Helping parents make confident choices

Are any illegal drugs safe to use when pregnant?

Cannabis, crack cocaine, LSD, speed, ecstasy, heroin - how will illegal drug use in pregnancy harm my baby?

Published: March 28, 2019 at 10:37 am

In a nutshell

No - avoid all illegal drugs


The expert view

It’s hard to accurately estimate how many pregnant women use illegal drugs, but research from the US suggests it could be around 5%.

Of this, around 3% of the mums-to-be questioned had used cannabis in pregnancy, and around 1% had taken cocaine.

"Do please speak to your doctor or antenatal team if you are taking recreational drugs," says MFM’s GP Dr Philippa Kaye. "Our job is not to judge you but to try and help you get the help which you may need to stop taking drugs and to keep you and your baby safe, so please speak to your antenatal team."

So, what are the risks if you have taken illegal drugs?

Well, there are risks – and the advice is always to avoid all illegal drugs – but if you shared a joint at a party before knowing you were pregnant then there’s probably no need to panic.

But regular use of illegal drugs can have effects on your health, and your baby’s development.

It’s definitely worth talking to your doctor or midwife if you are worried, and they can arrange for extra monitoring if they think it’s needed.


Cannabis is the most widely used illegal drug in the UK, but it is still a Class B drug which means possession carries up to 5 years in prison, an unlimited fine, or both.

The NHS warns that regularly smoking weed when pregnant can lead to a low birth weight baby, while a study in the Journal of Pediatrics found that babies’ neurobehaviour – such as memory and understanding - was affected by their mums’ use of cannabis during pregnancy.

Meanwhile, research has also found an association between using cannabis in pregnancy and the risk of children developing depression as they get older.

Another point to consider is the risks from tobacco if you use it to make a marijuana joint. Tobacco is addictive, and when smoked, releases chemicals which are known to cause cancer and other health issues. For your unborn baby, the risks include:

  • Low birth weight
  • Placental abruption (where the placenta comes away from the uterus wall)
  • Reduced oxygen flow
  • Birth defects including cleft palate
  • Sudden Infant Death Syndrome (SIDS)

Ecstasy, MDMA and amphetamines

Ecstasy and amphetamines (speed, whizz) are class A drugs and possession of them carries an unlimited fine and up to 7 years in prison.

These particular drugs are not considered to be physically addictive on their own, but some people can develop a psychological need for them, says Dr Kaye.

What's more, they have been linked to health problems for the baby, including:

  • Congenital heart disease
  • Poor growth in the womb
  • Low birth weight
  • Prematurity
  • Small head
  • Cleft palate
  • Biliary atresia (a blockage near the liver)
  • Gastrochisis (abnormal development of the stomach wall)

There’s also a risk of miscarriage when taking speed or pills.

Meanwhile, recent research suggests that babies may have development problems when their mums take MDMA in pregnancy.

Magic mushrooms

Also known as shrooms, these are a hallucinogen and can be eaten dried, steeped in tea, or cooked in food.

While there isn’t a lot of evidence out there about how they affect pregnant women and their babies, the most sensible and safest approach is to not use them. It's also worth bearing in mind the seriousness of taking a poisonous mushroom by accident as it can lead to severe health problems and even death.


Also a hallucinogen, taking LSD when pregnant has not been confirmed to cause specific defects in the baby, but there is evidence that it could lead to miscarriage.

Dr Kaye points out that the lack of information about the adverse effects of LSD "does not make it a safe choice."


The UK Teratology Information Service – which examines the effects of drugs and medicines on pregnant women and babies – points out that data is hard to come by for pregnant women using cocaine. It does however, highlight the risks associated with its use during pregnancy:

  • Increased risk of miscarriage
  • Placental abruption (when the placenta separates from the womb)
  • Premature labour
  • Growth problems
  • Sudden Infant Death Syndrome (SIDS)
  • Birth defects
  • Withdrawal symptoms in the baby after birth


While using heroin itself can lead to problems with low birth weight, premature birth, and even stillbirth, the circumstances that often go hand-in-hand with its use can also cause issues for mum and baby's general well-being.

Medically, this can include ill health such as infections, and on a personal level, difficulty with regular daily routines such as keeping antenatal appointments.

Between 48% and 94% of babies born after their mums used heroin have withdrawal symptoms, including sleeping and feeding problems, and weight loss.

"Babies are born essentially addicted themselves and would have withdrawal unless put on a gradual withdrawal programme while in hospital," explains Dr Kaye.

Mums on our forum say

"Visited the stop smoking nurse yesterday and my first day of going smoke free is Saturday.... Gulp!!!! Not quite sure how I'm going to cope with the ups and downs of cycle counting at the same time as giving up the weed," says bunnyhunny.

Adn speckle says: "I understand that it is an addiction, but why get pregnant when you know it will most likely affect your child??

"When I was pregnant with my ds, we had our tour of the hospital and while all of us were waiting outside, this girl came up to us saying how easy labour was when your smacked up!

"Honestly I couldn't believe it, she was boasting how she had saved the NHS money, cause she had her own pain relief.

"It sickens me! I love my all my children more than life it's self and i would go to the ends of the earth to protect them, these mothers don't seem to care.x"

Read more


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