ATLANTA — Most states are robbing small children from low-income families of a chance at quality education by spending too little on preschool child care and development, an advocacy group said Thursday.

Half the states spent $25 or less per child for such care in fiscal 1990. Even the 10 most generous in spending in fiscal 1990 fail to serve many children and families, the Children’s Defense Fund said in releasing a 50-state survey of such spending during its national conference in Atlanta.

The survey examined all state programs, including those with federal support, that help low-income families pay for child care or provide preschool education. The spending figures were determined from the entire number of children in each state.

The results ranged from $152.04 spent per child in Massachusetts to 24 cents in Idaho.

Maine spends $38.29 per child and ranks 17th in the nation.

“The primary conclusion of our study is not a single one of our states are investing adequately in the essentials for getting children ready for school,” said Marian Wright Edelman, president of the non-profit, Washington-based organization.

Half the states in the bottom third were from the South: Alabama, Arkansas, Georgia, Kentucky, Louisiana, Mississippi, Tennessee and Virginia. The majority of these states spent less than $12.50 per child, the survey found.

Another Southern state, Florida, ranked ninth nationally, spending $48.82 per child, three times as much as neighboring Georgia and more than four times as much as Alabama.