My wife and I got married in 1981 and stopped using birth control. Five years of worrying about unplanned parenthood and then it took a surprising amount of time for it to happen, first child in 1985, at age 31. And it wasn't for lack of trying. My wife was getting quite frustrated. At least we succeeded. Some couples try 100s of times and never make a baby. Finding out sooner  rather than later gives you time to pursue other options for having a family.