WASHINGTON – While 5% may not seem like a dramatic drop in participation in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), the decline in fiscal 2014 was the greatest for a single year since the program’s inception, according to a recent U.S. Department of Agriculture report.

Over the course of 2014, an average of 8.3 million people participated in the program, down 5% from the year before. Participation in the program peaked in 2010 and has fallen by 10% since then. The 5% decrease last year was the largest for a single year since the U.S.D.A. program was established in 1974.

The WIC program provides supplemental food, nutrition, education and health care referrals to low-income, nutritionally at-risk pregnant, breastfeeding and postpartum women as well as infants and children up to the age of 5. It is the nation’s third largest food and nutrition assistance program and cost $6.2 billion in fiscal 2014.

While the arc of the increase and decrease in WIC participation appears to mirror the downs and ups of the U.S. economy over the last several years, a different factor was cited by the U.S.D.A. as precipitating the decline.

“Falling WIC caseloads reflect the continued decline in the number of U.S. births, which began in 2008,” the U.S.D.A. said. “In 2013 (latest data available), 3.9 million babies were born in the United States, down from 4.3 million in 2007. Fewer births reduce the potential pool of WIC-eligible participants.

“Improving economic conditions in recent years may have also played a role in the decline in participation. The number of people in poverty fell in 2013, and in 2014, the unemployment rate decreased for the fourth consecutive year. Since applicants’ incomes must be at or below 185% of poverty, the number of people eligible for WIC is closely linked to the health of the economy.”

Looking deeper into the numbers, the U.S.D.A. said the number of children participating in WIC has fluctuated more than the number of women or infants. In fiscal 2014, the number of women in WIC fell by 4%, the number of infants by 3% and the number of children by 6%.

It was the fourth straight year that participation for all three groups fell. Before fiscal 2011, there was not a single year in which participation in all three groups fell.