The percentage of U.S. babies born outside of hospitals has reached its highest level in nearly 40 years, according to a new report from the Centers for Disease Control and Prevention.

In 2012, 1.36 percent of all U.S. births occurred outside of hospitals either at home, or at a birthing center up from 1.26 percent in 2011, according to the report.

Home and birthing center births have been on the rise since 2004, and the 2012 level is the highest since 1975, the report said. [7 Facts About Home Births]

Out-of-hospital births were more common among white women compared with other races: About 1 in 50 births to white women, or 2 percent, were outside of a hospital, compared to 0.54 percent of births to Asian or Pacific Islander women, 0.49 percent of births to black women and 0.46 percent of births to Hispanic women.

Northwestern states tended to have the highest percentage of home and birthing center births. More than 3 percent of births took place outside of a hospital in Oregon, Washington, Idaho, Montana and Alaska, and also in Pennsylvania.

Out-of-hospital births had lower rates of some complications, compared with births that took place in hospitals: The percentage of babies born preterm or at a low birth weight was lower among out-of-hospital births compared to hospital births, according to the report, from the CDC's National Center for Health Statistics.

This finding suggests that women who have a low risk of pregnancy complications (such as preterm birth) are making up a relatively larger proportion of out-of-hospital births than hospital births, the researchers said. In other words, women at higher risk for these complications are appropriately giving birth in hospitals instead of in other settings.

Lynn Johnson, a midwife and administrator of Womens and Childrens Services at Huntington Hospital in Huntington N.Y., said midwives have criteria that they use to determine which women are candidates for home births, and these are women who have normal-risk pregnancies.

Studies show that most home births are planned: In 2012, about 88 percent of home births in 36 states were planned, according to the report. Unplanned home births are more likely than planned home births to result in preterm birth or low birth weight babies, the researchers said.

Johnson said that giving birth at home or in a birthing center is becoming more popular in areas where it used to be less common. Johnson's hospital offers a hospital-based midwifery program, in which midwives and physicians collaborate in the woman's birthing experience, Johnson said

In the new report, the researchers did not look at the reason for the rise in home and birthing center births. They did note that the number of U.S. birthing centers increased from 170 in 2004, to nearly 2,050 in early 2013, the report said.

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