The mechanism of emergency contraceptive pills, whether one or two pills, is to inhibit ovulation and to change the thickness of the endometrium. The one-pill pill is relatively higher in dose and easier to take in clinical practice. The two-pill dose is smaller and a little more difficult to take clinically. So one tablet is more convenient, simpler and better. But whether it’s the one-piece or two-piece emergency contraceptive pill, it’s impossible to achieve 100% contraceptive effect in the clinic. Some people take the emergency contraceptive pill on time, but there is still a possibility of pregnancy, so women are advised not to use the emergency contraceptive pill as a regular contraceptive method, because after all, the side effects of the emergency contraceptive pill are still very big.