An ectopic pregnancy is an extrauterine pregnancy – when a fertilized which implants outside the lining of the uterus

Despite more than a decade of non-prescription availability of levonorgestrel, emergency contraception is currently underutilized in Australia and elsewhere in the world.

Three pharmacological methods of emergency contraception are available:

1.         Progestin-only (levonorgestrel) method:

●          This method differs from the older oestrogen / progesterone “Yuzpe”         regimen in having superior efficacy, and fewer side effects, notably less    nausea and vomiting.

It prevents 85% of expected pregnancies, (compared to 75% for the “Yuzpe” regimen) when used appropriately. 1

It must be taken within 72 hours, after unprotected intercourse or contraception failure

2.         Ulipristal:

●          This is a novel contraceptive agent.

            It is a selective progesterone receptor modulator (SPRM).

Ulipristal is effective for up to 120 hours (5 days) after unprotected intercourse or contraception failure.

3.         Yuzpe (oestrogen / progesterone) method:

●          The older Yuzpe method is now superseded, however it remains an option             if the levonorgestrel orulipristal are not available.  

Note that all methods of emergency contraception are more effective the sooner they are started after unprotected sexual intercourse.

Ulipristal is the most effective agent

Its advantages over levonorgestrel include:

1.         Its effectiveness for up to 5 days 4 (as opposed to 3 days of levonorgestrel)            following sexual intercourse.  

●          The efficacy of levonorgestrel decreases with time in the 72 hours following intercourse.

In contrast, the efficacy of ulipristal does not appear to be affected by time during the 120 hours following intercourse. 5           

Maintaining efficacy for five days after unprotected intercourse matches the survival time of sperm, providing another advantage over levonorgestrel.

2.         Its superior effectiveness:

●          Ulipristal is associated with a lower pregnancy rate than levonorgestrel.

It is reported to prevent two thirds of pregnancies within 72 hours of intercourse, compared to approximately 50 % of pregnancies prevented with levonorgestrel.

Its disadvantages compared to levonorgestrel include:

1.         Its major disadvantage (according to current knowledge) is its potential to harm established pregnancies. It is currently classed as a Category D drug with respect            to pregnancy. Levonorgestrel is safe in pregnancy. 

2.         Because of the above concern, pre-existing pregnancy must been excluded (i.e a negative beta HCG) before it is prescribed.     

3.         Because of the above two issues, ulipristal is not currently available “over the        counter” in Australia, but requires a doctor’s prescription.  

4.         It cannot be used in breastfeeding, (levonorgestrel can be used in pregnancy).   

See also separate document on:

●          Ulipristal (in Drugs folder).

Mechanism of Action

The precise mechanism of action is unclear for these agents

They are thought to predominantly work by preventing or delaying ovulation.

Alterations in the tubal transport of sperm and ova as well as the promotion of endometrial changes that discourage implantation may also play a role.


1.         Unprotected intercourse.

2.         Potential barrier method failure.

3.         Potential pill failure e.g. missed pills or vomiting.

The “morning after pill”, is not recommended for routine use as a contraceptive agent in sexually active women.

It is not as effective as conventional hormonal methods of contraception and is suitable only as an emergency measure.


Levonorgestrel Method

The progestin-only method of emergency contraception registered for use in Australia is:

●          A single dose of levonorgestrel 1.5 mg given within 72 hours of unprotected    sexual intercourse:


●          Levonorgestrel 750 micrograms orally, as an initial dose within 72 hours of    unprotected sexual intercourse, repeating the same dose 12 hours later.

A replacement dose of levonorgestrel is recommended if vomiting occurs within 2 hours of administration. 4

In Australia this is available from a pharmacy without a prescription.


●          It is possible to make up an equivalent dose with 25 tablets of a levonorgestrel    progestin-only minipill (levonorgestrel 30 micrograms per pill) followed by   another 25 tablets 12 hours later.

Also, although emergency contraception is more effective the earlier it is used, it has efficacy (although this is reduced with time, especially after 72 hours) up to 120 hours (five days) after unprotected sexual intercourse.

The progestin-only method of emergency contraception taken correctly prevents 85% of the pregnancies that would be expected from unprotected mid-cycle sexual intercourse.

Ulipristal method

Established pregnancy needs to be excluded.  

Ulipristal acetate as a single oral dose of 30 mg.

It should be administered within 5 days (i.e 120 hours), of unprotected sexual intercourse or contraceptive failure.

If ovulation has already occurred, ulipristal is no longer effective. The timing of ovulation cannot be predicted and therefore (even though it remains effective for 5 days) ulipristal should still be taken as soon as possible after unprotected intercourse.

If vomiting occurs within 3 hours of ulipristal ingestion, a replacement dose is recommended. 4

Yuzpe method

The Yuzpe method of emergency contraception consists of:

●          Four tablets of ethinyloestradiol 30 micrograms + levonorgestrel          150 micrograms taken within 72 hours of unprotected sexual intercourse,    and repeated 12 hours later.

Approximately 60% of women will experience nausea with this regimen, so an antiemetic should be prescribed at the same time.

The Yuzpe method prevents 75% of pregnancies resulting from unprotected mid-cycle sexual intercourse.

Because the progestin-only method is more effective and has fewer adverse effects associated with its use, the Yuzpe method should be used only if there is no alternative.




Fellowship Notes

Dr Jessica Hiller LITFL Author

Doctor at Sir Charles Gairdner Hospital in Western Australia. Graduated from Curtin University in 2023 with a Bachelor of Medicine, Bachelor of Surgery. I am passionate about Obstetrics and Gynaecology, with a special interest in rural health care.

Physician in training. German translator and lover of medical history.

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