For years, more babies were born to Christian women than to women of any other religion, but not for much longer: Islam is expected to take the global lead by 2035, according to a report released on Wednesday documenting the coming ebbs and flows of world religions.

Even as they change rank, Christianity and Islam are projected to expand their hold on the world’s newborn population from a combined 64 percent of all babies born from 2010 to 2015 to 71 percent of those born from 2055 to 2060, according to the report, prepared by the Pew Research Center.

That baby boom will largely be driven by regional trends in age and fertility, according to Alan Cooperman, director of religion research at Pew.