Catherine Price
Midwife

Catherine is the co-administrator of www.birth.com.au and the co-author of Birth the book, with childbirth educator Sandra Robinson. She holds a Masters Degree in Women's Health and has, since 1987, worked in all birth settings with women, their partners and families on their journey to parenthood. Catherine still 'catches' babies part-time at Sydney's Royal Prince Alfred Hospital and is married with two sons.

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Please note, a selection of queries and answers will be published on this page. Emails cannot be answered personally.

Cannabis and pregnancy

Question

I want to know the effect cannabis can have on trying to fall pregnant and the unborn baby? I would appreciate any information you have.

Answer

The effects of cannabis on fertility are not fully known. Besides decreasing a person's sex drive, it may reduce the sperm count in men and perhaps interfere with the regularity of the woman's menstrual cycle. THC (the chemical derived from cannabis that gives the person a 'high') is thought to be stored in higher concentrations in women than in men. This is because women have a higher percentage of body fat. It takes about a month after use for all the THC to leave a person's body.

During pregnancy, TCH passes from the woman's bloodstream to her baby through the placenta. Cannabis is not known to cause birth defects, but there are concerns that it may affect the baby's brain and nervous system development (as this is something that continues to develop throughout the whole pregnancy). Research studies indicate that unborn babies exposed to cannabis may be more likely to exhibit behavioural changes as older children. These children may be more impulsive, hyperactive and have attention difficulties, affecting their learning ability. Some studies have found that babies born to women who used marijuana regularly during pregnancy tend to be lighter in weight, shorter in length and have a smaller head circumference at birth.

Babies born to women who regularly use cannabis up until their baby is born may take longer to adjust to the light in the room and startle more easily. They may also have varying degrees of tremors (or the shakes) in the early days and initially not sleep as well.

Breastfeeding is best for your baby and if you do smoke cannabis, this should not be a reason to stop breastfeeding. However, cannabis is fat-soluble (meaning it dissolves in fat) and breastmilk is high in fat content, meaning that large amounts of THC can be passed through the breastmilk to the baby for several hours after the mother smokes cannabis.