Substances of abuse




Alcohol is a teratogen which increases the risk of foetal abnormalities and damages the developing central nervous system. Consuming alcohol at any time during pregnancy has the potential to damage the developing foetus. 
Heavy drinking during early pregnancy increases the risk of foetal abnormalities and miscarriage. Binge drinking (drinking more than 5 units of alcohol over a short time period) in early pregnancy can have a harmful effect on the development of the central nervous system.
Foetal alcohol syndrome (FAS) refers to foetal damage caused by the mother drinking alcohol during pregnancy. Symptoms include microcephaly, delayed development, growth failure and certain facial abnormalities. The developmental delay can vary from mild learning or behavioural problems to a severe mental retardation. According to a Finnish study, children whose mothers drank more than 10 units per week all presented at least one symptom caused by the mother's alcohol use.
The amount of alcohol which could be safely consumed during pregnancy is not known. The best alternative is not to drink any alcohol during pregnancy.


Repetitive or heavy drinking while breastfeeding can have a harmful effect on the child's development. The alcohol levels in breast milk correspond to the maternal blood alcohol level. When alcohol is infrequently used in small amounts, it is unlikely to harm your baby. However, frequent or heavy drinking can expose your baby to harmful amounts of alcohol.




Smoking during pregnancy increases the risk of premature birth, low birth weight, placental abruption (premature detachment of the placenta) and stillbirth. Nicotine affects blood circulation by constricting the blood vessels, including the placental blood vessels. Disorders in the placental circulation affect foetal oxygen supply. Smoking is also likely to increase the risk of birth defects such as cleft lip and palate and cardiac defects. Smoke contains various chemicals including several carcinogenic substances and carbon monoxide, which is known to cause foetal hypoxia.

Furthermore, several studies have shown a connection between maternal smoking during pregnancy and the child developing learning difficulties and behavioural disorders at a later age.


Maternal smoking exposes the baby to carcinogenic substances indirectly and through breast milk. The child's infection risk clearly increases when there is smoke in the room. Nicotine accumulates in breast milk. However, the level of nicotine from nicotine products passed into breast milk and to the baby remains relatively low. Therefore, nicotine replacement therapy does not prevent breastfeeding.




Cocaine and amphetamines (including Ecstasy) affect blood circulation by constricting the blood vessels. Placental circulation disorders may cause temporary embryonic or foetal hypoxia, which in turn causes developmental and growth malformations in various organs, and other problems. An increased risk of developmental cardiac disorders seems to be associated with the use of amphetamines and ecstasy during pregnancy. The risk of premature birth, placental abruption (premature detachment of the placenta) and stillbirth is associated with the use of amphetamines and cocaine. Babies of women who use cocaine are sometimes stiff and trembling and have a piercing wail (stiff baby syndrome).

These substances share a similar mechanism of action, and therefore a potential risk of malformations is associated with the use of any of these substances in early pregnancy. These substances are also likely to have long-term effects on the developing central nervous system.

Heroin use is clearly associated with low birth weight and stillbirth. Withdrawal symptoms in a newborn baby can be severe and may appear only a month after birth. Replacement drug therapy should never be initiated without appropriate medical supervision.

Using cannabis products may have a harmful effect on foetal growth. Tetrahydrocannabinol (THC) passes through the placental barrier, causing higher carbon monoxide levels in blood circulation than smoking. Study results indicate that foetal exposure to cannabis products may cause permanent changes in the function of the developing central nervous system.


Cocaine, ecstasy and amphetamine may cause permanent neural damage and life-threatening cardiovascular disorders to a breastfed baby. Babies can receive a harmful dose in breast milk. Mothers using these substances should not breastfeed their children.

Heroin accumulates in breast milk. Heroin levels in breast milk may be much higher than in the mother's circulation. Exposure poses a serious threat to the baby, and therefore mothers using heroin should never breastfeed their babies.

THC, the active ingredient in hashish and marijuana, accumulates in breast milk. The accumulated levels found in breast milk can be 10-fold to concentrations detected in maternal circulation. Regular exposure to THC can have a harmful effect on the development of the child's central nervous system, and therefore mothers using cannabis products should never breastfeed their babies.

LSD is transmitted to the central nervous system and poses a clear risk to the child. Mothers using LSD should never breastfeed their babies.

Drug rehabilitation

Methadone and buprenorphine therapy can be used in the treatment of opioid-dependent pregnant women. These medications may cause long-term withdrawal symptoms in the newborn baby.

Both buprenorphine and methadone pass into breast milk in very small amounts, and replacement drug therapy is typically not contraindicated while breastfeeding. However, the decision on whether to breastfeed the baby or not should be made together with the treating physician and the baby should be closely monitored so that any adverse effects can be detected without delay.