Well, if the Philippines becomes a US state, then the demographic transition happens earlier and the Filipino population would probably never reach 100 million in the first place.
Here are the relevant statistics. Note that in OTL 1960, the average Filipino woman had seven children!
If the Philippines become a U.S. state, then they'll have a higher standard of living compared to OTL, and thus a lower birth rate. Plus, if the Philippines gain statehood then a lot of Filipinos would probably emigrate to the continental United States, further reducing the population.
By the present day, I expect the population of the Philippines would be about 40 or 50 million (rather than 100 million as in OTL).