Cannabis is the most commonly used illicit drug amongst women of reproductive age or by women who are pregnant.

Even though there has been little research into the effects of cannabis use upon the unborn child, it is strongly recommended that pregnant women do not use alcohol or any other drug due to the potential harmful effects on the developing baby.

Can cannabis use affect fertility?

Heavy use of cannabis has been linked to decreased fertility in both men and women. In females, there is evidence that cannabis use may disrupt the menstrual cycle. In males, cannabis is thought to decrease sperm quality and testosterone levels. It is also thought to decrease the ability of sperm to move quickly and has been linked to sperm abnormalities.

These factors can make it difficult for a woman to become pregnant.

Can cannabis use affect pregnancy?

THC (delta-9-hydrocannabinol), the psychoactive ingredient in cannabis, is known to pass from the mother to the developing foetus through the placenta. This means that the foetus is affected by any amount of cannabis taken by the pregnant woman, placing it at a greater risk of complications occurring.

Any form of smoking can disrupt the supply of oxygen and nutrients to the foetus, which can result in premature birth. Women who smoke cannabis at least once a week are more likely to give birth to babies with a lower birth weight, which may place the child at a higher risk of developing breathing problems and possible infections.

There is evidence supporting damage caused by smoking tobacco during pregnancy, including:

• miscarriage
• still-birth
• Sudden Infant Death Syndrome (SIDS)

Because most people who smoke cannabis also smoke tobacco at the same time, it is believed that these complications could also occur if a woman smokes cannabis and tobacco during pregnancy.

Can cannabis use affect the baby?

There is some evidence that babies born to women who use cannabis during pregnancy are more likely to startle, have higher levels of tremors and may not see as well compared to those babies who are not exposed to cannabis. These symptoms, however, are not evident after the first month.

Other studies have found that in the first six months of life, babies who have been exposed to cannabis in utero are also at greater risk of developing asthma, chest infections, and other breathing problems such as wheezing.

Can cannabis use affect breast milk?

When a breastfeeding mother uses cannabis, THC passes into the breast-milk and thus into the baby, where it can be stored in the baby’s fatty tissue for several weeks.

Using cannabis while breastfeeding may cause the baby to be unsettled and disrupt feeding cycles.

As a result, cannabis use should be avoided when breastfeeding.

Can using cannabis impact on pregnancy care?

Other problems can be experienced by pregnant women using cannabis because they are less likely to disclose their use of cannabis to health care workers. The stigma associated with their use, as well as fear, guilt and shame about what they may have exposed their unborn baby to, may prevent these women from giving a full history to their obstetricians or midwives.

This may impact on the quality of care for both the woman and her developing baby as health care workers do not have a complete history.

What can you do?

If you are planning to become, or are pregnant and using cannabis, then it is a good time to stop using.

If you have been using cannabis during your pregnancy, talk to your doctor or midwife about your use. With this knowledge they can help support you as well as give you the care you need. They will also be able to help you, or refer you to someone else who can help you cut down or quit your cannabis use.