What is the Morning After Pill?
The Morning-After pill, Plan B One-Step® (not to be confused with Ella) works by releasing a high dose of progestin (levonorgestrel) which is found in many birth control pills. It may work by preventing the egg and sperm from meeting by delaying ovulation. The pill must be taken within 72 hours after unprotected sex. Taking Plan B One-Step® does not reliably stop ovulation, so fertilization of the egg may still take place. However, by other effects, the medication then prevents the newly-formed life from settling into the uterus and continuing to grow, which some consider a form of early abortion.*
*Noe et al, Contraceptive efficacy of emergency contraception with levonorgestrel given before or after ovulation. Contraception. 2011 Nov;84(5):486-92.
Peck et al. Does levonorgestrel emergency contraceptive have a post-fertilization effect? A review of its mechanism of action. Linacre Q. 2016 Feb; 83(1): 35–51.