Download this fact sheet: Cannabis 3.17 [PDF: 422 KB]
Introduction
The most commonly used illicit drug by women of reproductive age and by pregnant women is cannabis. There is not a great deal of research into the effects of cannabis on the development of the foetus but it is known that tetrahydrocannabinol (THC), the psychoactive component of cannabis, crosses the placenta in humans and is stored in the amniotic fluid that surrounds the baby.
Cannabis use during pregnancy has not been associated with birth abnormalities but it is considered harmful to the baby. There is some evidence that exposure to cannabis in the womb affects a baby's behaviour and may cause long-term behavioural problems.
SIDS and asthma
Women who smoke cannabis are exposing their children to the same risks associated with tobacco smoke:
- an increased risk of Sudden Infant Death Syndrome (SIDS)
- an increased risk of developing asthma and breathing conditions.
Low birth weight
Cannabis use during pregnancy is associated with premature labour and a minor reduction in birth weight. Low birth weight is related to an increased risk of infections and breathing problems.
Breastfeeding
The THC in cannabis passes into the breast milk, attaches to the baby's fatty tissue and can stay in the baby's body for several weeks. It is believed that the drug may cause the baby to become unsettled and demand frequent feeding.
Behaviour, verbal ability and memory
Research has found that babies who are exposed to cannabis in the womb may be irritable, unsettled and have feeding difficulties. These babies are more easily startled, have higher levels of tremors, may not see as well and have a high-pitched cry. These symptoms are no longer present one month after the birth. However, it appears that exposure to cannabis in the womb does affect some aspects of behaviour beyond the baby stage.
Children who have been exposed to cannabis in the womb have been observed to have more behavioural problems as toddlers than children who haven't been exposed to cannabis. They perform poorly on tasks of visual understanding, language comprehension, sustained attention and memory. In school, these children are more likely to experience difficulties in making decisions, remembering things and remaining attentive.
Tests of teenagers who were exposed to cannabis in the womb revealed significant reduction in attention, memory of visual stimuli, analysis and understanding.
Intelligence
Exposure to cannabis in the womb does not appear to affect IQ. Research indicates that between the ages of nine and 16 years there are no differences in overall IQ scores between children who have and have not been prenatally exposed to cannabis.
What can you do?
It is a good idea to try to stop cannabis use if you are pregnant or planning to become pregnant.
If you have been using cannabis during your pregnancy:
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Talk to your doctor or midwife early in the pregnancy so that they can properly check the baby's health.
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Your doctor or midwife can also refer you to services for support.
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Try to reduce your use — any reduction to the amount you smoke will lessen the effects on the baby.
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The earlier in the pregnancy that you stop or reduce your use the better for the baby.
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If possible it is best to avoid using cannabis while breastfeeding.
More information
For more information on drugs and drug prevention contact the DrugInfo Clearinghouse on tel. 1300 85 85 84, email druginfo@adf.org.au, or visit our website www.druginfo.adf.org.au.