The calculator on this page can help you work out when you might expect your baby to arrive. As part of your antenatal care, your midwife will also offer you a dating scan that will give you a more accurate date for the birth of your baby.
The Philippines is the island state’s nearest entry point to Southeast Asia, a region it desperately wants to cultivate as an export resource. Beijing’s unrelenting efforts over decades to undermine the legitimacy of Taiwan – a country it sees as a province of its own – has left the island state without a membership in any international or regional trading bloc.
Since there doesn't seem to be any systematic error that could cause so many methods to agree with each other so often, it seems that there is no other rational conclusion than to accept these dates as accurate.