There is hardly anyone these days who doesn't know how harmful smoking is, and yet around 8.6% of women 25 to 29 years old admit to smoking while pregnant, and almost 11% of those ages 20 to 24 do.

On top of that, up to 5% of women say they smoke marijuana while pregnant, according to the American College of Obstetricians and Gynecologists.

According to a new study in the International Journal of Epidemiology, those smokers are 2.6 times more likely to give birth prematurely compared to nonsmokers.

And when the baby is born, it is four times more likely to be small for its gestational age, and at risk for a roster of serious complications including infection, respiratory distress, vision and hearing problems, developmental delay, and cerebral palsy.

Premature babies are missing out on the final, important weeks or months of development of their brain, lungs, and liver. Babies born before 32 weeks are at the highest risk for disability and death.

If you’re a smoker and are thinking about becoming pregnant or are pregnant, there are many resources available to help you quit and protect your fetus from life-long health issues. Also, if your partner smokes, secondhand smoke can harm the baby too.

For everyone around a pregnant woman, and pregnant women themselves, quitting ASAP is the smart move. Check out free quit-coaching, a free quit plan, free educational materials, and referrals to local resources at 1-800-QUIT-NOW and "Become a Smokefree Woman" at women.smokefree.gov.