» RELATED: Is light drinking while pregnant really dangerous?
California, which boasts the lowest smoking rates overall, also had the lowest rate of expecting mothers smoking (1.6 percent).
According to the report, other states with low reported numbers (less than 5 percent) include Arizona, Connecticut, Hawaii, New Jersey, New York, Nevada, Texas, Utah, and D.C.
In Georgia, 5.6 percent of pregnant women reported smoking while pregnant.
» RELATED: Just one cigarette can lead to daily smoking, study says
"These levels do vary widely by state, maternal age, race and Hispanic origin, and education, but any amount of smoking during pregnancy is too much," Patrick Drake, lead author of the CDC report, told CNN.
The prevalence was highest among women aged 20 to 24 (10.7 percent) and among non-Hispanic American Indian or Alaska Native women (16.7 percent). Rates decreased with increased education among women with a completed high school education or higher.
Women with a bachelor’s degree or higher had a prevalence of smoking during pregnancy of 1 percent or less.
» RELATED: Why pregnant women should be careful around cats
Duke University School of Medicine professor Dr. Haywood Brown told CNN that some of the states with high rates of pregnant women smoking, such as West Virginia and Kentucky, also have some of the highest rates of infant mortality.
"The linkages between smoking and infant mortality and prematurity are real," Brown said.
Because the new CDC data is self-reported, the prevalence of smoking while pregnant could actually be underreported.
According to the CDC, some of the risks of smoking during pregnancy include:
- Smoking makes it harder to get pregnant to begin with.
- Women who smoke during pregnancy are more likely to have a miscarriage.
- Smoking while pregnant can also negatively affect the placenta, the source of the baby's food and oxygen.
- Smoking can lead to babies being born too early or have low birth weight. This makes it more likely the baby will be sick and will have to remain in the hospital for a longer time.
- Smoking during and after pregnancy is a risk factor of Sudden Infant Death Syndrome (SIDS).
- Babies born to women who smoke are more likely to have a cleft lip or cleft palate.
Read more at CDC.gov.