It will stop the ovulation before it happens. One of Plan Bs jobs is to delay ovulation preventing the egg from joining with a sperm.
Plan B How It Works
If you take it within 24 hours of unprotected sex it is 95 effective.
Is plan b effective after ovulation. If you take it between 48 and 72 hours of unprotected sex the efficacy rate is 61. Plan b works at any point in the cycle. In a minority of cases when there is a low risk of pregnancy from intercourse early in the fertile period and Plan B is taken promptly it may actually stop ovulation.
Plan B has a 95 chance of preventing pregnancy if you take it within 24 hours. Plan B is FDA approved for use up to 72 hours after unprotected sex. What Research Shows The majority of the research reveals that using Plan B does not cause any changes in the lining of the uterus endometrium.
Plan b prevents ovulation so of course if youve already ovulated it wont affect course of cycle. If you take it within 72 hours you have up to an 89 chance. That just means that if a woman needs emergency contraception after sex which she should only need about once or twice in her entire lifetime because she uses another reliable birth control method at all other times when babies are not desired she need not worry about what time of month it is.
Wondering whether youre within the window to take Plan B. Plan B should work you took it plenty soon enough. Also it has been known to prevent pregnancy even after ovulation so that just goes to show that plan B is a VERY effective preventive measure against pregnancy So whats the verdict.
In fact some sources including Planned Parenthood just say they flat-out dont work after ovulation. The sooner you take Plan B the more effective it is. Kivimakic 21 Aug 2016.
If Plan B is taken early in your cycle it probably does have the suggested upwards of 89 effectiveness but closer to mid-cycle probably not and after ovulation. In fact studies show that when taken after ovulation Plan B does not decrease the rate of pregnancy. This is because you cant prevent ovulation if its already happened.
Enter the date and time you had unprotected sex below. Plan B or emergency contraception works similarly. The effectiveness of taking Plan B after ovulation is uncertain.
It appears that Plan B is most effective prior to ovulation but after ovulation things get iffy and even experts cant seem to come to an agreement on its efficacy. If you take it after youve ovulated it can still work but instead of preventing ovulation altogether it can prevent a fertilized egg from attaching to the uterine wall. The sooner you take it the better it works Plan B helps prevent pregnancy before it starts by temporarily delaying ovulation when taken within 72 hours 3 days after unprotected sex.
It can be used up to 120 hours after but the further out from intercourse the less effective it will become says Bender. Its nearly a pointless measure. The problem after taking after ovulation is that the effectiveness falls from 80 into the 40 range.
It does have a higher failure rate then birth control pills and the manufacturer recommends you use a reg birth control and only use it if something happens like you were using condoms and it broke. When taken within 72 after unprotected sex Plan B works to prevent ovulation. It can prevent pregnancy if taken within 72 hours and preferably within 12 hours of unprotected sex.
Plan B works fine before during or after ovulation. They can work up to five days after but as time passes they get less effective. If you already ovulated and had sex before or during ovulation an egg may have been fertilized.
For an individual patient the effectiveness of Plan B decreases with every passing hour because the chance of missing ovulation increases as time passes and science has demonstrated Plan B doesnt work after ovulation occurs. And ECPs definitely dont work as well once ovulation has already happened. If ovulation has already occurred and fertilization is able to occur pregnancy results If you cant tell.
