Why is the UN arbitrarily inflating population predictions?

Why is the UN arbitrarily inflating population predictions? | LifeSiteNews.com: The U.N. Population Division says the world’s population will reach 9.3 billion by 2050 — several hundred million higher than earlier predictions. Not only that, the UN now claims that the numbers will continue to grow until the end of the century, reaching 10.1 billion in 2100.

But these new predictions fly in the face of all we know about human fertility. Every last one of the factors affecting fertility — with the sole exception of advances in reproductive technology — are moving in an anti-natal direction. Factors like age at marriage, age at first child-bearing, educational levels, etc., are all tending to lower fertility. Birthrates are falling everywhere, farther and faster than anyone thought possible several decades ago.