Why does emergency contraception delay periods?

Hormonal effects. Plan b is used for unprotected sex with contraceptive failure. It works using female hormones. Plan b can prevent the ovary from releasing an egg, thicken cervical mucus which makes it harder for the sperm to reach the egg and thins the lining of the uterus to prevent implantation.

Related Questions

Help plz! Can planned parenthood emergency contraception pill delay your period the following month?

Yes. Taking Plan B may delay your 1st period by about a week. It is best to do a pregnancy test and be safe. It should not have any effect on the period after that. Read more...

If I took emergency contraception a day before my period was expected, when can I expect to get my period? I heard ec can delay it.

Yes it can. Plus emergency contraception would rarely be needed for intercourse the day before your expected period. Why don't you use protection and not have to worry about these things? It also significantly reduces your chances of acquiring an std or hiv. Read more...
Early or delayed. Emergency contraception can cause the next period to come sooner or later, but after that, cycles should go back to normal. Be sure to use regular birth control if you are sexually active. There are many options. It's good that you knew about emergency birth control, but regular birth control is more effective. Read more...

I took emergency contraception on June 14 & bled on June 28 (around 5 days delayed) Was this my period or withdrawal bleeding? I felt all the PMS

Response to Plan B. It is your body's response to the hormonal changes induced by the emergency contraceptive. Whether you want to count that as your period is really not important. What it means is that you are not pregnant, but does nothing in predicting your next cycle as things will be thrown off the next month because of use of the hormones. Read more...

Can Plan B contraception pill delay a period for one whole month?

Yes. Depending on what time of your cycle you take the plan b. If you take a morning after pill in the first half of your cycle, you may have an earlier than usual period. If you take it in the second half of your cycle, you may have a much later than usual period. Check with your doctor if you have any other symptoms or concerns. Read more...
Usually not. Plan b, because it is hormonal, can cause period to be delayed. But that is usually a few days or a week. A missed period can be caused by stress, pregnancy, hormones such as thyroid being off, for instance. Often this will go back to normal on its own. If not get checked. Do consider checking a pregnancy test just to be sure. Read more...
Yes. Completely possible for the Progesterone in Plan B to delay period for one month. If you're worried because you've missed your period, you may want to consider taking a home pregnancy test. Otherwise, period will self-regulate and get back to normal soon. Good luck! Read more...