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Emergency Contraception - information
for health professionals
Emergency contraception can be used to reduce the risk
of pregnancy after unprotected sex.
Health professionals have a major role in facilitating early
access to emergency contraception (EC) to maximise its chance
of effectiveness. Information and education about the method
should be raised opportunistically in a range of reproductive,
contraceptive and sexual health consultations. Research overseas
has found that easy access to emergency contraception including
keeping an emergency script or supply at home does not decrease
the use of regular contraceptive methods.3
Emergency contraception can be used following sexual contact
where there is a risk of an unintended pregnancy.
Indications include:
- unprotected intercourse
- failure of a barrier method
- sexual assault
- potential pill failures
- recent use of suspected teratogens
Oral steroid emergency contraception
Levonorgestrel-only method
Levonorgestrel-only emergency contraception should be used
as the method of choice unless a woman is considering insertion
of an IUCD. A recent study has shown that this method is highly
effective and has minimal side effects.1
Dose: Two doses of levonorgestrel 750 ug taken 12 hours
apart.
- Postinor-2 one tablet and another tablet 12 hours later;
- Microlut or Microval twenty-five (25) tablets and twenty-five
(25) tablets 12 hours later.
Postinor-2 has TGA approval for use as an emergency contraceptive
in Australia.
Combined oestrogen-progestogen method
The combined oestrogen-progestogen regimen commonly referred
to as the Yuzpe method is no longer commonly used as an emergency
contraception method as it is less effective and has more
side effects compared to the levonorgestrel method.1
It can be used if other methods are not readily accessible;
eg if it is difficult for the woman to obtain a prescription
or supply of the levonorgestrel method, but she has a supply
of suitable combined oral contraceptive pills at home.
Dose: Two doses of 100ug ethinyl estradiol and 500ug levonorgestrel
taken 12 hours apart.
- 4 tablets stat of Nordette or Microgynon 30 (or generic
equivalent) and another 4 tablets 12 hours later.
As nausea and vomiting are very common with the Yuzpe method,
an anti emetic, to be taken 30-60 minutes prior to the hormonal
doses, should be supplied/prescribed with this regimen.
Both levonorgestrel and Yuzpe methods have been shown to
be most effective when commenced within 12-24 hours of sexual
intercourse, with commencement of the first dose recommended
before 72 hours.1
A recent study, using the Yuzpe regimen, found that emergency
contraception may still be effective (though to a lesser degree)
in preventing pregnancy, when commenced up to 120 hours after
intercourse.2
Mechanism of action
The exact mechanism of action for emergency contraception
methods is not well understood. Hormonal methods are thought
to prevent or delay ovulation. They may also interfere with
ovum and sperm transport, fertilisation and implantation.4
There is no evidence that emergency contraceptive pills
act to disrupt an implanted pregnancy.
Effectiveness
The average risk of pregnancy from midcycle intercourse
is 20% to 30%. Pregnancy rates of less than 3% have been recorded
with both hormonal methods when commenced within 72 hours
of unprotected sex.
- Recent evidence suggests that the efficacy of both hormonal
methods is greater the earlier after exposure the first
dose is given.1
- With the levonorgestrel method, the rate of pregnancy
is 0.4% if started within 24 hours and 2.7% if started within
72 hours. The rates for the Yuzpe method are 2% and 4.7%
respectively.1
- There is no day after the stated last menstrual period
for which a clinician can be sure that unprotected sexual
- intercourse does not carry a risk of conception. In a
28 day cycle, days 8-18 carry a higher risk of conception.
Contraindications
The World Health Organisation and the International Planned
Parenthood Federation have stated that there are no known
contraindications to the use of hormonal emergency contraception,
so there is no need for a medical history or physical examination
before providing it.5
Side effects
Nausea, vomiting, dizziness and fatigue are the commonest
side effects of emergency oral steroid contraception. The
incidence of these is significantly lower with the levonorgestrel-only
method.1
- Less common side effects including headache, breast tenderness
and lower abdominal pain can occur with this method.1
- No adverse effects on foetal development have been reported
with the method in cases where pregnancy has occurred.
Frequency of Use
- Emergency contraceptive pills (ECP) should not replace
the use of regular contraception, as the cumulative pregnancy
rate for frequent use of ECP is higher than with regular
contraception. However, if unprotected sex occurs in a cycle
where the ECP has already been used it can be used again.
- Women should understand that the use of the ECP cannot
protect them from the possibility of pregnancy if unprotected
intercourse occurs later in the cycle.
- In cycles, where unprotected intercourse has occurred
more than once, ECP can be used, although efficacy will
be influenced by the time interval since the first act of
unprotected intercourse. The woman must understand that,
if a pregnancy has already occurred, the ECP will not be
effective.
Drug interactions
Hepatic enzyme inducing drugs
Hepatic enzyme inducing drugs enhance the metabolism of
levonorgestrel and ethinyl estradiol. If a woman taking these
drugs (e.g. phenytoin, carbamazepine, rifampicin, griseofulvin)
uses emergency hormonal contraception the recommendation is
to double each dose. This increases the risk of side effects.6,7,10
Antibiotics
Antibiotics taken concurrently with hormonal emergency contraception
are unlikely to alter its efficacy and no alteration in dose
is advised. The exceptions are the enzyme inducers rifampicin
and griseofulvin as detailed above.6,7,10
Follow up
- Women should be advised that, after hormonal emergency
contraception, their menstrual period should occur within
one week before or after the expected time. If menstruation
is delayed for more than one week or if it is much lighter
than normal, emergency contraception may have failed and
the woman should have a pregnancy test.5
- Emergency contraception is not intended to induce a withdrawal
bleed.
- The woman must be advised to return if the bleed is significantly
different from her usual menstrual bleed. This includes
light or intermittent bleeding or bleeding delayed by more
than a week.
- There is no protection from pregnancy after postcoital
hormonal therapy so abstention from intercourse or barriers
should be strongly advised until ongoing contraception has
taken effect.
- Oral contraception can be started immediately or with
the next menstruation. If oral contraception is started
immediately it is not considered to be effective until 7
hormone pills have been taken. In this situation careful
follow up to exclude pregnancy is advised.
- If a woman has forgotten oral contraceptive pills and
is using postcoital steroidal contraception, she can continue
her oral contraceptive pill. She is not considered to be
safe until 7 hormone pills have been taken.
Emergency contraception for potential pill failures
Missed combined pill mid-packet.
When active pill taking has been established for seven consecutive
days contraceptive protection will only be lost if 7 active
pills are missed. Postcoital contraception would be over-treatment
when 1-3 pills are missed mid-packet.10,7 Emergency
contraception may be justified empirically where there is
a high level of anxiety.
Prolonged pill free interval.
The pill free interval is considered prolonged when active
pills are missed either from the first and or last week of
the packet. A careful history of all missed pills should be
taken in order to calculate the length of the pill free interval.
Emergency contraception may be indicated when the pill free
interval is extended to eight or more days. This would include
missing one or more of the first or last seven pills in any
combination.
Missed progestogen-only pill.
Emergency contraception may be indicated if unprotected
intercourse takes place at any time from the time of the first
missed or late pill (ie. pill taking delayed by more than
three hours) to 48 hours after pill taking is resumed.
Women who present for emergency contraception have had
unprotected intercourse and may be at risk of acquiring a
sexually transmitted infection.
It is important to assess the STI risk and manage accordingly.
Copper Bearing IUCDs
Copper bearing IUCDs provide an effective method of postcoital
contraception. The failure rate is less than 1%.10
Careful assessment and counselling should take place before
insertion is decided upon. The IUCD is not suitable for women
who have risk factors for pelvic inflammatory disease.
An emergency IUCD can be inserted at any time in the cycle
provided the earliest episode of unprotected intercourse occurred
no more than 5 days previously. Where the earliest episode
of unprotected intercourse was more than 5 days previously,
an IUCD can be considered up to 5 days after the calculated
earliest day of ovulation (ie. up to day 19 of a 28 day shortest
cycle by history). This limit is well within the period before
implantation.6,7 If the woman does not wish to
continue using the IUCD as a contraceptive method, it may
be removed at the time of the next period. If hormonal contraception
has been commenced, the IUCD may be removed after 7 active
pills have been taken.
Breastfeeding and emergency contraception
Fully breastfeeding women who are amenorrhoeic (no vaginal
bleeding after 56 days postpartum), have a negligible risk
of pregnancy in the first 6 months postpartum.8
If a breastfeeding woman taking the progestogen-only pill
misses a single pill, the risk of pregnancy is very low particularly
if she is amenorrhoeic.
The progestogen-only regimen or IUCD are the only suitable
alternatives for breastfeeding women who require emergency
contraception.
Future Developments
A single dose of 10 mg RU486 (mifepristone) used within
72 hours of unprotected intercourse has been shown to be highly
effective in protecting against pregnancy with fewer side
effects than the other hormonal methods.9 RU486
is not available in Australia at present.
Further Reading:
- 1. Task Force on Postovulatory Methods of Fertility Regulation.
(1998). Randomised controlled trial of levonorgestrel versus
the Yuzpe regimen of combined oral contraceptives for emergency
contraception. Lancet, 352, 428-433.
- 2. Rodrigues, I., Grou, F., & Joly, J. (2001). Effectiveness
of emergency contraceptive pills between 72 and 120 hours
after unprotected sexual intercourse. American Journal of
Obstetrics and Gynecology,184(4), 531-537.
- 3. Glasier, A. & Baird D. (1998).The effects of self
administering emergency contraception. New England Journal
of Medicine,339(1),1-4.
- 4. Croxatto, H. et al. (2001). Mechanism of action of
hormonal preparations used for emergency contraception:
a review of the literature. Contraception, 63, 111-121.
- 5. International Planned Parenthood Federation. (2000).
IMAP statement on emergency contraception. IPPF Medical
Bulletin, 34(3),1-2.
- 6. Kubba, A. & Wilkinson, C. (1998). Recommendations
for clinical practice: emergency contraception. British
Journal of Family Planning, 23(4), insert 1-8.
- 7. Kubba, A. & Wilkinson, C. (1998). Emergency contraception
update. British Journal of Family Planning, 23(4), 135-137.
- 8. Gross, B., Burger, H. & the WHO Task Force on
methods for the natural regulation of fertility. (2002).
Australian New Zealand Journal of Obstetrics and Gynaecology,
42(2),148-154.
- 9. WHO Task Force on Post Ovulatory Methods of Fertlity
Regulation (1999). Comparison of three single doses of mifepristone
as emergency contraception: a randomised trial. Lancet,353,
697-702.
- 10. Guillebaud, J. (1999). Contraception today (3rd ed.).
London: Martin Dunitz.
- 11. Weisberg, E. (2001). Emergency Contraception. Current
Therapeutics, Oct, 47-49.
Disclaimer
Family Planning Queensland
(FPQ) has taken every care to ensure that the information
contained in this publication is accurate and up-to-date at
the time of being published. As information and knowledge
is constantly changing, readers are strongly advised to confirm
that the information complies with present research, legislation
and policy guidelines. FPQ accepts no responsibility for difficulties
that may arise as a result of an individual acting on the
advice and recommendations it contains.
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