The airline said passenger Aida Alamillo was 35 weeks pregnant when she went into labor aboard the Monday flight and she was assisted by three nurses and the plane's cabin crew.
Flight Purser Antonia Castaneda wrote in her Flight Incident Report the baby gave a "loud cry" upon his birth and "started to breast feed" after a few moments.
The plane landed about 4 hours after the birth and the mother and her newborn were taken to the Mills Peninsula Hospital in Burlingame.
Philippine Airlines said in-flight births are rare, but all cabin crew members are trained to handle childbirth.
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