A new study has found that girls are 67 percent more likely to be diagnosed with autism if her grandmother smoked while pregnant.
Pregnant Woman With Cigarette Ash Tray
Credit: Africa Studio/Shutterstock

We know smoking is hella-bad for you for a host of reasons. But now it seems lighting up may adversely impact not just your health, and that of your kids, but even your grandchildren’s.

A new study out of the University of Bristol finds that a girl’s autism risk is linked to her maternal grandmother’s smoking habits. In fact, when researchers looked at 14,500 participants who were born in the 1990s, they found a girl was 67 percent more likely to display traits associated with autism, such as challenges with communication, if her mother’s mother smoked. Both boys and girls were 53 percent more likely to be diagnosed with autism if their maternal grandma lit up.

So why does whether your grandma smoked matter? The research points to the theory that if a woman is exposed to nicotine while she’s in the womb, it could affect her eggs and later, her offspring’s development.

Professor Marcus Pembrey, one of the paper's authors, further explains,“In terms of mechanisms, there are two broad possibilities. There is DNA damage that is transmitted to the grandchildren or there is some adaptive response to the smoking that leaves the grandchild more vulnerable to ASD.” He adds,“We have no explanation for the sex difference, although we have previously found that grand-maternal smoking is associated with different growth patterns in grandsons and granddaughters.”

Professor Jean Golding, another author, added this takeaway from the research, “We already know that protecting a baby from tobacco smoke is one of the best things a woman can do to give her child a healthy start in life. Now we've found that not smoking during pregnancy could also give their future grandchildren a better start too.”

Of course, this latest data provides only one of many possible causes of autism. But it seems pretty much nothing good at all comes out of hitting the filter.

Melissa Willets is a writer/blogger and soon-to-be mom of 4. Find her on Facebook where she chronicles her life momming under the influence. Of yoga.