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Women's Health




This article outlines the methods used to prevent pregnancy after unprotected sexual intercourse, including the "morning after pill" and copper iucd.


Emergency contraception gives women a second chance to prevent pregnancy if initial attempts fail or unprotected sex occurs.


The most common method of emergency contraception is also known as ‘the morning-after pill’. However this term is falling out of favour because of the myth it perpetuates that the pill is only effective when taken the morning after unprotected sex.


When may emergency contraception be required?


Emergency contraception may be needed in a range of different situations for example:


  • Consensual sex where no contraception was used
  • Contraception failure such as a missed oral contraceptive pill or a dislodged condom or diaphragm
  • Rape or sexual assault
  • Ejaculation onto the external genitalia


It goes without saying that emergency contraception should not be used as a primary method of preventing pregnancy. If women find that they are needing to use emergency contraception frequently it is a good idea to figure out why this is and which preventative contraception methods may work for them to prevent further use.


Overview of emergency contraception


In New Zealand, the two most common forms of emergency contraception are the oral hormonal pill and the copper-bearing intrauterine device (IUD).


The hormonal pill contains 1.5mg of levonorgestrel and is known as Postinor-1. It is taken as a single dose. Less commonly used is Postinor-2 which is half the dose of Postinor-1 taken on two different occasions. It was found to be less effective than taking one single dose.


An older method of emergency contraception that is no longer common practice because of its side effects is the Yuzpe regimen in which patients take multiple doses of a combined oestrogen–progestogen pill. This may be a considered option if access to Postinor-1 is limited although this is rare in New Zealand as most pharmacies will stock the medication.

Postinor-1 is now available over-the-counter to women of any age: this means it can be purchased from a pharmacy without a prescription.


When should emergency contraception be started?


The oral emergency contraceptive can be taken up to 72 hours after unprotected sex and the IUD can be inserted up to 5 days after unprotected sex. The sooner the emergency contraception is initiated, the lower the risk of pregnancy.


Although there are periods during the menstrual cycle when women are more fertile than others, there is never a time where unprotected sex is risk-free. This is because many women have unpredictable cycles and sperm can stay viable in the vaginal tract for a long period of time.


Using Postinor-1


The oral emergency contraceptive Postinor-1 can be used within 72 hours of unprotected sex. The sooner after sex the pill is taken, the higher the chances of pregnancy prevention. Studies estimate that the reduction in pregnancies following use of the pill are 95% within 24 hours, 85% within 25-48 hours and 58% after 49-72 hours.

A recent study has suggested that the medication is still effective at 120 hours, although 72 hours is the commonly recommended cut-off.


How does it work?


Postinor-1 works by delaying ovulation (the release of the egg from the ovary). The hormone contained in the pill prevents the development of an unfertilised egg, delaying its release and therefore its ability to be fertilised by sperm. The less developed the egg is to begin with (which is dependent on the time in the cycle), the greater the effectiveness of the pill at preventing pregnancy.


The pill has no effects on the lining of the uterus or embryo development. In other words, the pill prevents fertilisation and implantation of the egg rather than stopping an embryo from developing. If pregnancy has occurred prior to EC use, the pill does not interfere with the developing embryo or cause an abortion. The pill does not increase the risk of spontaneous abortion in the future.


The pill is general really well tolerated by women. The most common side effect is nausea and it helps to take the pill with food to reduce this.


What happens after?


After taking Postinor-1 it is recommended that a barrier method of contraception (i.e. condoms, diaphragms) is used until the next menstrual period begins. However some doctors may choose to start a regular contraceptive pill immediately to avoid a future risk of unwanted pregnancy.


If a woman is already on the oral contraceptive she may continue to take it as usual.


After taking Postinor-1, the timing of the next menstrual period may be disturbed but will normally be within 7 days of the expected time. If it is more than 7 days overdue then pregnancy should be ruled out with a pregnancy test.


It is reasonable to do a follow up pregnancy test for peace of mind in any event.


Medical situations where Postinor-1 is not recommended (consult with your family doctor about this)


  • Known pregnancy
  • Severe liver problems
  • Malabsorption problems (such as Crohn’s disease) as this may affect the absorption of the pill
  • Severe hypertension, ischaemic heart disease, stroke
  • Diabetic complications (such as kidney, eye or nerve damage)
  • Breast cancer


Any conditions that prevent people from being able to take the oral contraceptive pill safely such as blood clots will also impact on the safety of Postinor-1. Consult with a doctor about this if this is the case.

Postinor-1 is safe to take while breastfeeding and while it is detectable in breast milk 8-12 hours after ingestion, it has not been reported to have any adverse effects on the baby and does not impair breast milk production.


Vomiting within three hours of taking the pill may render it ineffective and it is important to see a doctor or pharmacist again in this case.

Reasons to need 2 x Postinor-1 (i.e. levonorgestrel 3mg)


The metabolism of Postinor-1 is sped up by simultaneous use of certain medicines sometimes referred to as ‘liver enzyme inducers’. The common medicines that are in this group are:


  • Phenytoin, carbamazepine, primidone, barbiturates
  • St John’s Wort
  • Rifampicin
  • Griseofulvum


Women who take these medicines and require emergency contraception and choose to use Postinor-1 will need to be given 2x 1.5mg to take as a single dose within 72 hours of unprotected sex. The IUD is usually seen as the preferred option for women taking liver enzyme inducers.




Despite being the less commonly used method of emergency contraception studies show that copper IUDs are in fact the most effective method. Studies have suggested failure rates as low as 0.1%. Despite this, many clinicians don’t routinely offer insertion of the IUD, partly because of the invasive nature of the treatment.


The intrauterine device should be inserted within 5 days of unprotected sex or 5 days of predicted ovulation. This window of time is longer than the oral hormonal pill so is often used if the treatment window is missed for the Postinor-1.



How does a copper IUD work?


The copper IUD impairs the motility and viability of sperm. The copper also creates a toxic environment in the uterus so that a fertilised egg cannot implant on the wall of the uterus.  


An IUD is suitable for almost all women, some reasons why women can’t have an IUD inserted include:


  • Cancers of the genital tract

  • Untreated chlamydia or gonorrhoea

  • Current cervicitis

  • Suspicion of current pregnancy


What are the risks?


There are some risks associated with insertion of the IUD including a small risk of perforation (1 in 1,000 women) and an increased risk of infection over the first three weeks (1.4-9.7 in 1,000). Women may also experience bleeding between periods after the insertion of the IUD, increased pain with periods and slight increases in the volume of blood shed at menstruation. Around 5% of users need to get their device reinserted.


In the rare event that pregnancy occurs despite IUD use, the IUD should be removed as soon as possible if feasible. Pregnant women with a retained IUD are at a higher risk of spontaneous abortion, preterm delivery, the risks decrease once the device is removed but don’t return as low as baseline levels.  


What happens after?


An emergency IUD can be removed after the next menstrual period but many women choose not to get the IUD removed at the next menstrual period and continue with it as long term contraception.


The doctor who inserts the emergency IUD will usually prescribe antibiotics to eliminate the risk of possible infection spreading into the pelvis from any potential sexually transmitted infection.


Not all GPs are trained or experienced in the insertion of IUDs – it is best to check first before assuming that they will be able or prepared to insert one if it is needed. Family planning clinics are often a good alternative.






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