David Crary of the Associated Press reports that for the first time in a decade, there was a notable increase last year in the number of U.S. children in foster care, according to new federal figures released Wednesday.

The annual report from the Department of Health and Human Services tallied 415,129 children in the foster care system as of September 30, 2014, up from about 401,000 a year earlier. The peak was 524,000 children in foster care in 2002, and the number had dropped steadily since 2005 before rising slightly in 2013.

The long-term drop resulted primarily from shifts in the policies and practices of state and county child welfare agencies. Many shortened stays in foster care, expedited adoptions and expanded preventive support for troubled families so more children avoided being removed from home in the first place.

HHS offered no immediate explanation of why the numbers had risen.

“We are concerned about any increases in the foster care numbers, and we are working hard with our state partners to better understand the reasons behind the increase,” said Rafael Lopez, commissioner of the department’s Administration on Children, Youth and Families.

Of the children in foster care a year ago, 52% were boys. Twenty-two percent were Hispanic, 24% black and 42% white. Just under 108,000 of them were available for adoption, up from 104,493 in 2013.

During the 2014 fiscal year, 50,644 children were adopted from foster care, roughly the same as in 2013, while 22,392 youths in their late teens aged out of the system without being placed with a permanent family.

Three-fourths of the children in care last year were living with foster families, while 14% were in group homes or institutions. On the day the data was reported — Sept. 30 — 4,544 foster children were listed as runaways.