One in five white woman have smoked cigarettes while pregnant, according to a new government study released today.

The report, conducted by the Substance Abuse and Mental Health Services Administration, showed that 21.8 percent of pregnant white women ages 15 to 44 had smoked a cigarette within 30 days of when the survey was conducted.

Those numbers contrasted with 14.2 percent of black women and 6.5 percent of Hispanic women of the same age.

"When pregnant women use alcohol, tobacco, or illicit substances they are risking health problems for themselves and poor birth outcomes for their babies," SAMHSA Administrator Pamela S. Hyde said in a statement. "Pregnant women of different races and ethnicities may have diverse patterns of substance abuse. It is essential that we use the findings from this report to develop better ways of getting this key message out to every segment of our community so that no woman or child is endangered by substance use and abuse."

The rate of alcohol use during pregnancy among black and white women was about the same: 12.8 percent and 12.2 percent respectively. Only about 7.4 percent of Hispanic women reported drinking alcohol while pregnant.

Black pregnant women were more likely to use illegal drugs than white and Hispanic pregnant women: about 7.7 percent of blacks, 4.4 percent of whites and 3.1 percent of Hispanics reported using drugs at least once in 30 days prior to the survey.

A mother's smoking habit is one of the key risk factors for Sudden Infant Death Syndrome (SIDS), according to Dr. Ari Brown, author of the book "Baby 411."

"A mom who smokes has less circulating oxygen in her body and thus, so does her unborn baby," Brown wrote in the book. "This is called fetal hypoxia. There is also less blood flow to the uterus and placenta, and therefore to the baby. Lastly, nicotine goes right through the placenta and circulates in the bloodstream of the fetus."

Smoking increases the risk of a small fetus who doesn't grow properly, a placenta that implants in the cervix, a placenta that pulls from the uterine wall prematurely, preterm birth and low birth weight.

As for alcohol, Brown wrote in her book that the latest research shows that much smaller amounts (one to two drinks a day) may adversely affect a child's birth weight, attention, behavior and IQ. And fetal alcohol syndrome is the number one preventable cause of intellectual disability in children.

"Bottom line: don't drink. Good news: most women actually lose their taste for alcohol during pregnancy, so most pregnant women won't be craving a margarita with Mexican food anyway," he said.