People queue up to be the first to buy legal marijuana as Canada becomes the largest country in the world to legalise cannabis for recreational use.

Smoking cannabis to wind down after the kids are in bed is no different to drinking a glass of wine, a researcher says.

University of Wellington lecturer and criminologist Fiona Hutton, who has researched gender and drug use and drug law reform, said both substances helped parents relax after busy days working and looking after their children.

The only difference was that cannabis wasn't a legal drug like alcohol, though those using the drug in that way shouldn't be criminalised, she said.

Instagram/Caitlin Fladager Canadian blogger Caitlin Fladager says smoking weed has helped her to become a better parent.

Her comments came in response to a Canadian blogger who said on Wednesday smoking marijuana daily helped her be a better mother.

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​Caitlin Fladager, who has 289,000 followers on Instagram, posted an image of herself smoking a joint next to a sign that reads, "Mom truth: Weed should be just as acceptable as a glass of wine". The mum of two said it was OK to smoke weed, which is legal in Canada, after kids were in bed.

​"Marijuana has helped me so much, especially when it comes to being a mom," she wrote.⁣⁣

"I have never been the most patient with my two kids. Weed makes me a better mom, as I get a good night sleep after I smoke."

SUPPLIED University of Wellington lecturer and criminologist Fiona Hutton says parents shouldn't be criminalised or stigmatised for choosing cannabis over a glass of wine once the kids are asleep.

It also helped her manage her anxiety and quit alcohol, she said on the post, which has had more than 26,000 likes and many positive comments.⁣⁣

"It's so funny to me how frowned upon marijuana is. No one looks twice when a mom says she enjoys "mom juice" aka wine, after her kids are in bed. But when a mom says she smokes weed, it's a huge shock," she said.

Hutton said mum who use cannabis to relax after a hard day shouldn't be criminalised and stigmatised.

"The likelihood is that some mums in New Zealand will already use cannabis to wind down after a busy day, given that there are over 400,000 regular cannabis users in New Zealand," she said.

"Cannabis is also less harmful than other drugs in society like alcohol and tobacco ... so mothers who use cannabis rather than alcohol could be doing themselves less harm than if they drank a glass of wine instead."

The benefits of marijuana were the same as alcohol, she said.

"Relaxation, coping with the strains of parenting and enjoying something for yourself – heaving a metaphorical sigh of relief as the children finally fall asleep".

PlunketLine manager Anne Marie Morris said evidence showed the effects of second hand smoke - including marijuana smoke, were always detrimental and parents were advised not to smoke at all.

GETTY-IMAGES Fiona Hutton says it's likely some mums in New Zealand are already use cannabis to wind down after a busy day, given that there are more than 400,000 regular cannabis users in New Zealand,

"If you do smoke, don't smoke around your child, and this includes even if your child isn't around; don't smoke somewhere they will be, like your home or your car," she said.

"It is also important to note that all children need to be safe in the care of the adult who supervises them. Therefore if an adult is under the influence of a substance that impairs their judgement and ability to provide safe care, it is important to have a plan for a sober adult to do so."