The Shulchan Aruch writes that one should not wipe one’s self after the restroom using one’s right hand. The Mishna Berurah writes that the reason behind this is that one performs the mitzvah of tying one's teffilin using his right hand. Additional reasons mentioned in the gemora are that the Torah was given with the right hand, people eat with their right hands, and one learns and teaches Torah with one's right hand. Even though some of these reasons do not apply to women, since others do, the commandment applies equally to women. (Ben Ish Chai and Rabbi Yakov Emden) Other Poskim are lenient (Machzik Bracha).
Today, given that people use toilet paper many poskim (Shulchan Aruch Harav) say that this halacha is no longer applicable. However, others still recommend that the left hand be used.