I’m concerned that spironolactone can cause birth defects. If I want to become pregnant in the future, how long should I stop the medication before trying?

You can simply stop the medication once you want to start trying to get pregnant. There is no need to wait several months before trying. Spironolactone works by blocking the effects of androgens, otherwise known as “male hormones.” If you become pregnant with a boy while taking it, it may affect his sexual development. That’s why you should not get pregnant while taking spironolactone. But sexual development does not begin in utero until week 6 of pregnancy, and spironolactone has a short half-life (<17 hours). Since it’s quickly metabolized out of your system, there is no need to wait several months after stopping spironolactone before trying to get pregnant. 

Spironolactone does not affect your ability to get pregnant. There are no long term effects on your reproduction.