Does the Morning-after Pill Delay Your Period? Your Questions Answered

Many women who take the morning-after pill (MAP) find themselves trapped in a waiting game as the date of their expected period approaches. For many women, they assume that the only reason for a delayed period is pregnancy, but this isn’t always the case.  

If you’ve already taken the morning-after pill, waiting for your period can be an anxious time. Remember that there is little you can do at this point, and that options are available to you regardless of the outcome. All you can do is stay informed about your health, your cycle, and what to expect.

To that end, let’s talk about how the morning-after pill works, why Plan B may delay periods, when to take a pregnancy test, and when to come see us here at Clinic 66 so that we can advise you on the next steps.

Clinic 66 offers discreet telehealth appointments to women across Australia. Whether you want to know why the morning-after pill delays your period, you are seeking advice on termination, access to the abortion pill, or you need guidance from a trusted sexual health clinic, we are here to support you.

How the morning-after pill works:

Contrary to what you may have heard, the morning-after pill (MAP) doesn’t terminate pregnancy in the early stages. What it does do is prevent a pregnancy before it happens by delaying ovulation through the use of levonorgestrel, a synthetic progestogen. This delay in ovulation means that the egg never releases, is never fertilised, and is never implanted in the uterus.If you have already ovulated in your cycle, Plan B or the morning-after pill (MAP) will not be effective.

There are three types of emergency contraception available in Australia. Levonorgestrel has been used for some time and needs to be taken within 72 hours of unprotected intercourse. Ulipristal acetate (UPA) is a newer form of MAP, slightly more effective, and can be taken up to 120 hours (five days) after unprotected intercourse. Both types of MAP work by delaying ovulation and are available from pharmacies without a prescription.

The third type of emergency contraception is the copper intrauterine device (IUD), which must be inserted by a trained healthcare provider within five days of unprotected sex. The copper IUD does not prevent ovulation but is highly effective (over 98%) and can remain in place for up to 10 years, depending on the type of device. It may make your periods heavier or longer, but if you usually have light periods and prefer not to use hormones, it may be a suitable option for you.

The morning-after pill is highly effective, but it must be taken promptly after intercourse. The longer you leave it, the less likely it is to be effective. 

It’s also worth noting that Plan B may be less effective in individuals with a BMI of 30 or higher. Your GP will be able to advise you if this is likely to be an issue for you, and provide you with alternatives.

Does the morning-after pill delay the period?

So, does taking the morning-after pill delay your next period? Yes, this is not only normal but expected, and there is no reason to assume you are pregnant if your period is slightly delayed.

Why does the morning-after pill delay your next period? The pills contain levonorgestrel or ulipristal , which delay ovulation, in turn delaying the luteal, and menstrual phases that follow. For most people this will mean a delay in menstrual bleeding (although it’s not unusual to experience spotting).

How long does the morning-after pill delay your period?

The delay of ovulation may trigger a delay in menstruation by several days or a week. Some studies have indicated that the impact on your period will be based on when in your cycle you took Plan B.

When to expect your next period after taking the morning-after pill:

Remember that no two women are the same, nor are their cycles. If you have a regular cycle, ovulation usually occurs midcycle. If you have an irregular cycle, it is a lot more difficult to predict ovulation.  

In general, however, here’s what you can expect based on when you took Plan B:

Timing of Plan B Intake	Effect on Ovulation	Impact on Next Period
Before Ovulation	Delays or inhibits ovulation	Period may be delayed by up to a week or more; hormonal disruption can cause changes in timing and flow
After Ovulation	Less effective: as the egg has already been released	Period may arrive on time or slightly earlier; hormonal disruption can still cause changes in timing and flow
During Luteal Phase	May delay ovulation or alter luteal phase	Period may be delayed; hormonal disruption can cause changes in timing and flow

Not sure what phase you were in? You may be able to work backwards if you know your last period, as you likely ovulated about 14 days following the end of menstruation, however, this depends on the length of your usual cycle. People with PCOS may not ovulate regularly or in a predictable way.

Regardless of when you took Plan B, you will need to wait until your period has failed to arrive to accurately test for pregnancy.

When to take a pregnancy test?

The morning-after pill (MAP), or Plan B, has a 91% chance of preventing pregnancy when taken immediately after sex. Unfortunately, the only way to know if the morning-after pill has worked as intended is to wait for your period, which may take several weeks.

There is no point in taking a pregnancy test before your predicted period, and you should remember that the process of implantation takes several weeks. A pregnancy test will likely return a negative result regardless as the pregnancy hormone (hCG) will not be detectable before the first day of a missed period.

If you haven’t started your period within one week of your normal menstruation date, then you should take an at-home pregnancy test. 

If the result is negative, wait a few weeks. With any luck you’ll get your period. If not, take another test. Try not to stress, as stress in itself can cause your period to be delayed! 

If you return a positive pregnancy test, you have options.

When to call Clinic 66:

If you want a copper IUD inserted after unprotected sex, call us immediately so we can fit you in as soon as possible for insertion. 

If you return multiple negative results but your period does not return, then it may be worth chatting to your GP about delayed menstruation and what might be causing the continued interruption in your cycle.

If you return a positive result, and want to explore your options with a trusted women’s health clinic, Clinic 66 can help. We’ve been delivering a comprehensive range of sexual and reproductive health services for over 25 years, and we pride ourselves on our compassionate, discreet and 100% non-judgmental approach.

We understand that some people find dealing with their sexual health concerns confronting. But we can comfortably say, that when it comes to sexual health issues, there’s nothing we haven’t seen before.

You have nothing to fear and most certainly nothing to feel ashamed of.

If you require any further advice on delayed periods, the morning-after pill, or pregnancy, contact us today.