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Emergency Contraceptives: Frequently Asked Questions Answered

Will emergency contraceptives delay my period?

Emergency contraceptives (EC) also known as “morning-after pills” are synthetic hormones in a higher concentration that are expected to help prevent pregnancy.

Your regular menstrual cycle is controlled by the release of various hormones in different concentrations depending on the stage you are in your cycle.

As such, increasing the amounts of certain hormones at times when they should normally be low can result in some physiological changes and this is the basis for pregnancy prevention by contraceptives.

Are emergency contraceptives effective?

The answer is yes but it has to be taken within the recommended time frame after having an unprotected sexual intercourse. 

Emergency contraceptives act by varying mechanisms;

  • by inhibiting or postponing ovulation,
  • thickening of the cervical mucus and otherwise altering the environment to hinder sperm migration and
  • some other potential effects on hormonal levels (estrogen and progesterone) as well as on physical and biochemical properties of the endometrium of the uterus (womb).

Based on the above mechanism, it means that, the earlier the contraceptive is taken the higher its effectiveness. Emergency contraceptives may not work after implantation or fertilization (including ovulation) has occurred, and that is why timing is crucial in taking emergency contraceptives. 

Can emergency contraceptives cause spotting

Spotting also known as irregular bleeding or bleeding that is not associated with menses may occur in some women after taking the emergency contraceptives.

The bleeding may be light or little and doesn’t usually last longer than 72 hours. This is a side effect of the drug.

However, vaginal bleeding that is heavier or persistent for more than 72 hours may be due to some other complications or may be menses. When it happens like this, one should consult with a doctor to investigate. 

Can emergency contraceptives cause infertility?

One of the myths about emergency contraceptives is that one may become infertile with their use. They may temporarily delay conception when abused by using them on a daily basis or as a regular form of contraception which is not safe and recommended.

This is because ECs are manufactured in higher strengths, unlike the routine daily oral contraceptives that are usually prepared in lower strength for safety purposes. 

Can emergency contraceptives cause lower back pain?

Lower back pain is a side effect of some of these emergency contraceptives like Ulipristal acetate (EllaOne). Also, women who use the intra-uterine emergency contraceptives may have back pain as a side effect. However, common emergency contraceptives containing levonorgestrel have not been reported to cause back pain.

A study done by Hanneke A, et al concluded that, in adult women, hormonal and reproductive factors are associated with musculoskeletal pain in general. Factors related to increased estrogen levels may specifically increase the risk of chronic lower back pain. 

One of the emergency contraceptives called the Yuzpe regimen contains estro-progestin for preventing pregnancy after unprotected sexual intercourse. The Yuzpe regimen consists of two doses of combined oestrogen-progesterone pills, with each dose containing 100 micrograms of ethinyl oestradiol and 1.0mg of norgestrel giving a total amount of active progestin of 0.5 mg per dose.

This regimen which has now fallen out of favor recently has a higher dose of estrogen and probably may affect hormonal balance resulting in chronic back pain with long term use. However, there are no studies relating long term use of the yuzpe regimen and lower back pain. 

Persistent lower back pain after an emergency contraceptive use needs further investigation and one must see the doctor without delay. It may be as a result of ectopic pregnancy and this needs urgent attention. 

Can emergency contraceptives cause miscarriage?

As stated earlier, emergency contraceptives are not effective after implantation. Emergency contraceptives are not harmful in pregnancy and therefore will not routinely cause miscarriage.

However, manufacturers advise that they should be avoided once pregnancy is confirmed and in the case of intra-uterine devices; they should be removed within the first trimester. 

Considering the variety of emergency contraceptives available (including levonogestrel (LNG), copper IUD (intrauterine device), ulipristal acetate), some of them at higher doses put one at risk of miscarriage.

In the case of continued pregnancy, doses of levonorgestrel greater than 1.5 mg can have some unwanted effects on the foetus and may lead to miscarriage. IUDs have the potential to cause miscarriage when inserted after implantation.

What do emergency contraceptives do to your body?

Emergency contraceptives are hormonal with the exception of the copper IUDs and as a result are expected to affect the normal hormonal levels in the body.

In emergency contraception, studies have shown that the hormonal ones (levonorgestrel, norgestrel) delay ovulation, and impair luteal function. They may also increase the thickness of the cervical mucus or affect sperm migration and function in the genital tract, thereby preventing fertilization of an egg [E. R. Gunardi and B. Affandi, 2014]

Ulipristal acetate is thought to inhibit or delay ovulation. A clinical trial showed that it could delay ovulation for 24-48 hours even on the day of the luteinizing hormone (LH) peak. Other mechanisms include reducing the endometrial thick­ness, delayed endometrial maturation, and alterations in the progesterone–dependent markers required for implantation.

These effects may subsequently inhibit implantation because the uterus will be less receptive to the trophoblast [P. Stratton, 2010].

Combined emergency contraceptive pills work by inhibiting implantation of a fertilized egg [S. Mittal, 2014]. Other postulated mechanisms include delaying or suppressing ovulation, interfering with corpus luteum function and making changes in the endometrium that prevents implantation [Gemzell-Danielsson K, et al 2014].

Why does some emergency contraception fail?

As already indicated, emergency contraceptives must be taken within a period when they have been verified as effective (at most 72 hours for levonorgestrel and 120 hours (5 days) for ulipristal acetate.

There is still a probability of failure when taken immediately after an unprotected sexual intercourse because they do not have hundred percent efficacy.

However, the earlier one takes the EC the better the chances of preventing an unwanted pregnancy. As a result, one should not delay taking her medication immediately after an unprotected sexual intercourse.

Why does emergency contraception delay your period?

Changes in menstrual bleeding and duration including delays are some of the common side effects of emergency contraceptives. Some women may report up to 7 days delay or shortage in their menstrual cycle. The cycle usually returns to the original cycle after the next two or three complete cycles.

The delay observed is associated with delays in ovulation associated with the hormonal emergency contraceptives from a study conducted by Gainer E. 

Is emergency contraception effective during ovulation?

The mode of action of the hormonal emergency contraceptives is to delay ovulation from occurring and also change the consistency of the uterine endometrium and fluidity.

Therefore, depending on the type of emergency contraceptives that are used if hormonal, may exhibit reduced efficacy or fail after ovulation. Some females may even develop ectopic pregnancy.

However, an emergency contraceptive like the copper IUDs still exhibit high effectiveness during and after ovulation. 

Do emergency contraceptives cause weight gain?

Emergency contraceptives do not cause weight gain since they are made for a single use and not for use on a regular basis. However, if their frequency of use is increased, they can lead to weight gain.

What emergency contraception is best for overweight?

The emergency contraceptives are not a regular or routine pill that should be taken on a regular basis. Some birth control pills may cause weight gain in a minority of women but a single dose of an emergency contraceptive is not expected to result in weight gain.

Hence, there is no need to worry about weight gain when one is deciding on which emergency contraceptive to use. 

When can emergency contraception be used?

Emergency contraceptives are used to prevent pregnancy after an unprotected sexual intercourse either from a deliberate consent or sexual abuse. 

When is emergency contraception most effective?

Emergency contraceptives are most effective when taken immediately after an unprotected sexual intercourse. 

Within 72 hours of unprotected sex, ulipristal acetate is at least as effective as levonorgestrel and estimated to be 98.2% to 99.1% effective [Glaser. A. F. et al, 2010]. Ulipristal maintains consistent effectiveness up to 5 days (120 hours) of unprotected intercourse, whilst the effectiveness of levonorgestrel declines when given more than 48 hours of unprotected sexual intercourse.

Within 72 to 120 hours, ulipristal acetate is more effective than levonorgestrel [Glaser. A. F. et al, 2010].

What does the 72hours of emergency contraceptives mean?

It means counting from the time when unprotected sexual intercource ended, every single hour that elapse till you count 72 hours (from day 1 of sex up to day 3)

Why does long term use of combined contraceptives lead to decreased menstruation?

In the early stages of oral combined contraceptives intake, there is usually a shortened period of endometrial proliferation. 

However, after taking the pills for a while, the endometrium starts thinning up and this results in a reduced menstrual flow. Prolonged use can eventually lead to a complete absence of menstrual flow.

How long will it take for menstruation to return to normal after stopping the use of the contraceptive

It has been found out that the delay in ovulation will resume to normal in about the next three menstrual cycles after stoppage of the oral contraceptives.

But for the complete stoppage of menstruation (amenorrhea) or anovulation, it may persist for about 6 months after discontinuing the contraceptives and it may be longer than that in some women.


S. Mittal, “Emergency contraception-Potential for women’s health,” e Indian Journal of Medical Research,vol. 140,1, p. S45, 2014.

E. R. Gunardi and B. Affandi, “Serum levonorgestrel con­centration and cervical mucus viscosity aer six months of monoplant implantation,” Medical Journal of Indonesia,vol.23, no. 1, pp. 25–29, 2014.

“World Health Organization website. Emergency contracep-tion. Fact Sheet. February 2016,” http://www.who.int/mediacen-tre/factsheets/fs244/en/, accessed on 20 July 2018.

K. Gemzell-Danielsson, T. Rabe, and L. Cheng, “Emergency Contraception,” Gynecological Endocrinology,vol.29, no.1,pp. 1–14, 2013.

A. F. Glasier, S. T. Cameron, and P. M. Fine, “Ulipristal acetate versus levonorgestrel for emergency contraception: A ran-domised non-inferiority trial and meta-analysis,” e Lancet, vol. 375, no. 9714, pp. 555–562, 2010.

Celia M. J. Matyanga and Blessing Dzingirai, 2018. Clinical Pharmacology of Hormonal Emergency Contraceptive Pills. 

Hanneke H. A et al, 2006. Hormonal and reproductive factors are associated with chronic low back pain and chronic upper extremity pain in women. The MORGEN study. 


Author at Wapomu.com

Dr. Abel Daartey is a pharmacist by profession, a teacher, and a mentor by nature. He enjoys reading scientific journals and articles and publications in neuroscience and related topics. He aims at churning out content that educates the public and health care providers in meeting the healthcare needs of the populace.

Chief Editor at Wapomu.com

MPSGH, MRPharmS, MPhil.

Isaiah Amoo is a practicing community pharmacist in good standing with the Pharmacy Council of Ghana who has meaningful experience in academia and industrial pharmacy. He is a member of the Royal Pharmaceutical Society, England, UK and currently pursuing his overseas pharmacy assessment programme (MSc) at Aston University, UK. He had his MPhil degree in Pharmaceutical Chemistry at Kwame Nkrumah University of Science and Technology. He has about 5 years’ experience as a community Pharmacist and has also taught in academic institutions like KNUST, Kumasi Technical University, Royal Ann College of Health, and G-Health Consult. He likes to spend time reading medical research articles and loves sharing his knowledge with others.

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