Jennifer Talbot, 43 passed through the airport immigration counter on Wednesday without declaring the baby boy, but was intercepted at the boarding gate by airline personnel who alerted immigration personnel.
Talbot was later turned over to the National Bureau of Investigation and the baby was given to government welfare personnel.
Ms Talbot, from Ohio, was unable to produce any passport, boarding pass or government permits for the baby, airport officials said.
Clad in an orange detainee shirt and in handcuffs, Talbot was presented to reporters in Manila on Thursday but did not issue any statement.
Talbot later presented an affidavit allegedly from the baby's mother, giving consent for the baby to travel to the US, but it had not been signed by the mother.
Officials said no government travel approval had been issued for the baby, prompting them to file human trafficking charges against her which carry a maximum penalty of life imprisonment.
Officials are searching for the baby's parents, who have been charged under a child protection law.