Police believe the infant may have been breathing at some point after being delivered by Hilda Figueroa, but do not yet have autopsy results, said Hart.

Also under question is the identity of the baby's father. Although Figueroa has given investigators a name, police are talking to several family members to determine who the father is and will conduct DNA tests to establish his identity, Hart said.

Police were directed to Figueroa's home after she sought treatment at San Mateo Medical Center Wednesday, saying she had delivered a premature, stillborn fetus at home. Hospital officials contacted police at 12:40 p.m., said Hart.

Officers found the child wrapped in plastic bags in the trash at Figueroa's apartment building in the 600 block of Buckeye Street.

Figueroa was arrested around 5 p.m. on Wednesday, Hart said.

Police reported that a medical examination showed Figueroa gave birth to a full-term baby. She allegedly said she delivered the child on Tuesday.

Parents or legal caregivers of newborns up to 3 days old may surrender them at hospitals and many fire stations with immunity from prosecution under California's Safely Surrendered Baby Law.

According to a January report to the California Legislature about the law, 128 babies were abandoned between January 2001 and September 2004. Of those, 105 were abandoned alive. But only 64 of the babies abandoned in this period were surrendered under the Safely Surrendered Baby Law, which dates to September 2001, according to the report.

Mothers who have abandoned babies under the law ranged in age from 15 to 42 years old, challenging the popular assumption that they are typically in their early teens, the report stated.

The report and other information about the Safely Surrendered Baby Law are available online at www.babysafe.ca.gov.