Sex Before Marriage

Many people say that sex is OK outside of marriage so long as you don't get pregnant.  Birth control makes this rather predictable.  My church counters with, "No sex until married." It is a solution that might have worked when people got married in their early teens.  But now people are waiting until their late 20s or even 30+.  Is the argument still relevant for waiting until marriage for these older more mature adults?  People wait because of economics, careers, debts, advanced degrees.  My church has never really had much of a handle or outreach to people after confirmation up to marriage preparation.  This is becoming a fifteen year gap.  Maybe if the church listens, this gap of people will tell the church what the people need.  It might make for some ambiguity.  Authority is allergic to ambiguity.   Answers to which no one listens is preferred to change.