At least 6 percent of pregnant women are battered by their spouses or partners, the Centers for Disease Control and Prevention said in a study released Thursday.
The estimate is the first based on sampling a large number of women. About 13,000 women who are representative of the populations in four states were asked just after they gave birth whether their husbands or partners physically hurt them during the preceding 12 months.
Dr. Julie Gazmararian, the leading author of the study for the centers, said that the numbers were underestimates because women were reluctant to admit being battered but that they were a good measure of the lower bound of what was occurring.
The states and the percentage of pregnant women who reported violence were: Oklahoma, 6.9 percent; West Virginia, 5.1 percent; Alaska, 6.1 percent; Maine, 3.8 percent.
A projection based on the numbers suggests at least 240,000 pregnant women are battered each year in the United States, or about 6 percent of all pregnant women.
"It is startling to see how many women are at risk, and especially during pregnancy, a time when women are bonding more with their mates," Gazmararian said in a telephone interview.
Dr. Linda Saltzman, a senior researcher in the government's research program on violence and its prevention at the Centers for Disease Control, says that when violence is reported, it is not known how best to intervene. The CDC has begun to study that problem.
The data, in the "Morbidity and Mortality Weekly Report," noted that estimates of violence against all women varied widely, ranging from 2.5-million to 12-million. Similarly, the number of pregnant women who are battered has been estimated to be as high as 17 percent.
The new figures showed that violence occurs in substantial amounts in all social groups, but occurs most frequently among people who are least educated, young, living in crowded conditions, unmarried and who have not gotten prenatal care.
Saltzman said it was important that doctors and other health care professionals routinely begin looking for signs of battering and asking women if they were battered when they came in for treatment for other conditions.
She said pregnancy was a particularly good time to check, as it was the time when women sought frequent medical care.