Now that cannabis is basically mainstream, few people bat an eye at parents hitting the vape or a joint after the kids go to bed. But what about moms-to-be who want to use cannabis? It turns out the answer is more complex than you might think.

A new study by researchers at the University of Auckland found that babies born to women who consumed marijuana actually scored better in one area of brain development.

The study of 165 children had the test group, aged four and under, watch moving dots on a computer screen. The kids were then asked to tell researchers which direction the dots were moving as a way to measure global motion perception.

According to The Chronicle, researchers found the scores were markedly better for kids whose mothers used cannabis in pregnancy, versus those who didn't. Maybe the most surprising? The more often the mothers smoked cannabis, and the larger the quantities, the greater the benefit to their offspring.

The study also discovered something else they say merits further study. Moms drinking alcohol led to worse testing scores overall for kids - and when both cannabis and alcohol were consumed, they cancelled each other out.

But that doesn't mean it's okay for pregnant women to light up, stressed the researchers.

All the well-known caveats about smoking - tobacco or cannabis - still apply. There is research indicating associations between marijuana smoking and lower birth weight, exaggerated and prolonged startle reflexes, and sleep disturbances in newborns, as well as a higher risk for complications in early pregnancy.

h/t The Chronicle, The NZ Herald