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Advances in Methods of Emergency Contraception

Overview of methods of Emergency Contraception
– Dr Suneeta Mittal, Professor, Department of Obstetrics & Gynaecology, AIIMS, New Delhi

The search for an ideal contraceptive which does not interfere with spontaneity or pleasure of the sexual act, yet effectively controls the fertility, is still continuing. Numerous contraceptive techniques are available, yet contraceptive coverage continues to be poor in India as most people are either ignorant or shy, or do not want to use a contraceptive continuously regardless of sexual activity for fear of side-effects (pill or intra-uterine device), or do not like to use methods linked with coitus (barriers like condom or diaphragm). Thus even when not planning for a pregnancy, exposure to unprotected sex takes place often, necessitating the use of Emergency Contraception, to avoid the potential hazards of pregnancy termination. This need may also arise due to failure of contraceptive method being used (condom rupture, diaphragm slippage, forgotten oral pills) or following sexual assault.

The risk of pregnancy following a single act of coitus varies from 4-25% depending on the time when intercourse takes place during the menstrual cycle. Risk is more when sexual exposure occurs close to ovulation.

Emergency contraception is really not a new concept . In the literature written 2000 years ago, we find evidence of various herbs to be used for the ‘morning after’. A number of ineffective folklore methods which are rather unscientific, like use of vaginal douching using different agents, blowing nose or jumping backwards have been used to prevent conception following unprotected coitus.

Mechanism of action

Several opportunities are offered during the reproductive process to interrupt the process of conception, rather than resorting to abortion. But, usually when couples fail to take precautions, they only keep hoping and praying that pregnancy would not take place and wait anxiously for luck and nature to decide their fate.

Emergency contraceptives act as interceptive agents i.e. ovulation, fertilization or implantation is prevented depending on the phase of menstrual cycle.

If used before ovulation, follicular maturation as well as ovulation is disrupted. Following ovulation implantation of blastocyst is interfered with by causing asynchronous endometrial maturation. Function of corpus luteum is also affected and progesterone surge does not take place. There is a fall in the level of endometrial carbonic anhydrase which is important for stickiness of blastocyst. Progesterone also acts by increasing intra-uterine pH. Copper IUD prevents implantation by a direct embryotoxic effect. Danazol acts as a luteolytic as well as prevents nidation and hampers decidualization. The GnRH analogues act by inhibiting LH secretion. Failure rate of Emergency Contraception is varying from 0-2.4% depending on the method used, interval between coitus and method use and relationship of coitus to ovulation. But all methods are ineffective once implantation has already occurred, thus these are not abortifacients.


A woman faced with the prospect of an unplanned and unwanted pregnancy can, in many cases, avoid the pregnancy by using Emergency Contraception. This term is used to describe methods which can be used post-coitally to prevent pregnancy following unprotected sexual act. These are also called ‘morning after’ methods, but can be effective if used within 3-5 days of sexual exposure.

These have also been called post-ovulatory methods, but need not necessarily be used following ovulation, and are useful in all phases of cycle. Emergency Contraception is not synonymus with ‘visiting’ or ‘vacation’ pill since other methods besides a pill are included in the gamut of EC.

A better definition proposed by Dr Paul van Look from WHO is - “Emergency contraception refers to a particular type of contraception that is used as an emergency procedure to prevent pregnancy following unprotected, possibly fertile intercourse”.


Several scientific methods are available for Emergency Contraception now and most of these are safe and effective.

High dose Estrogen : This was the first scientific method introduced in the 1960s. The method consisted of diethylstilbestrol (DES) being given in a dose of 50 mg per day for 5 days, subsequently dose was reduced to 10 mg per day. Association of DES with potential effects on female offspring resulted in a discontinuation of use of DES. Other estrogens like conjugated equine estrogen, ethinyl estradiol and depot estrogens were also used by various investigators. Though found effective in preventing pregnancy, high dose estrogen use is associated with a high incidence of side-effects, specially nausea and vomiting thus women sometimes fail to complete the prescribed course of treatment. Besides, menstrual pattern is disrupted following estrogen use and next period can be earlier with heavier flow. After treatment failure, 10% of pregnancies are likely to be ectopic, thus estrogens alone are no longer used as Emergency Contraception.

Estrogen-Progestogen combination : In 1972 Yuzpe and his colleagues evaluated a combined ethinyl estradiol and levonorgestrel pill each containing 50µg ethinyl estradiol and 0.5 mg of norgestrel, 2 tablets being given twice, 12 hours apart, within 72 hours of unprotected intercourse. This is commonly known as Yuzpe Method. This has fewer side-effects compared to high dose estrogen but still about 50% have nausea and 10-25% vomit. Currently, this is the most popular and easily available method. Regular dose oral contraceptive pill can be used as post-coital pill in prescribed dose. Currently available oral pills Mala-D and Mala-N containing 30µg ethinyl estradiol require 4 tablets to be given twice at an interval of 12 hours. There is no contra-indication to use of Yuzpe method.

Progestogens : Norgestrel as well as quingestanol have been tried and shown to be effective over a range of doses. The side-effects of progestogen only pills are less than combination pills. In low doses, progestogen may change the menstrual pattern. Current trials have shown progestogen only pill, containing 0.75mg, levonorgestrel (LNG) given in 2 doses 12 hours apart within 72 hours of unprotected intercourse, to be more effective with fewer side-effects compared to yuzpe method.

LNG has also been tried as 2 doses of 0.75mg, 12 hours apart upto 120 hours after sexual exposure, as well as, as a single dose of 1.5mg, again within 120 hours. The trial results are under publication.

Anti progestogens : These are anti-implantation agents when given post-coitally, menses inducers when given in luteal phase and abortifacients when given in early pregnancy. Several antiprogestogens have been tried. RU486 (mifepristone) has been found effective in a single dose of 600 mg, 100 mg and 10 mg when used as emergency contraception. In a comparative trial of RU486 with Yuzpe regimen, side-effects were less common with mifepristone but menstrual disturbances occurred more often.

Antiestrogens : Danazol has a direct luteolytic effect. A 400 mg dose repeated 12 hourly for 2 or 3 doses has been used with lesser side-effects as compared to Yuzpe regimen.

Centchroman : is an antiestrogen with no progestogenic, androgenic or antiandrogenic effect. It has been used as two 50 mg tablets given 12 hours apart within 72 hours. Main side-effect is ovarian enlargement and delay in menstruation causing confusion and tension. Adequate trials of Centchroman as an effective emergency contraception are yet to be conducted.

Intra-uterine Device (IUD) : Insertion of copper-T and copper-7 within 5 days of unprotected intercourse have been reported as a highly successful method for post-coital contraception. Copper-T is effective following even multiple coital exposures during a short interval and when delay is beyond 72 hours, making hormonal methods ineffective. IUD is particularly suitable for women who would like to continue using it as a regular contraceptive. Contra-indications to emergency IUD use are the same as regular use. In young nulliparous women or women with multiple sexual partners, there is a risk of pelvic inflammatory disease. Sometimes, irregular bleeding associated with IUD insertion may mask diagnosis of early pregnancy.

Calculation of Efficacy

Since possibility of conception is not there throughout the menstrual cycle, measuring pregnancy rate following EC use is not enough as a measure of efficacy. It is more important to calculate reduction in expected pregnancies. This is also called prevented fraction and is calculated by formula.

1–observed pregnancies
expected pregnancies

For calculating the expected pregnancies conception risk for each day of menstrual cycle is calculated by probability of conception on that cycle day. For estimation of probability of conception, a formula proposed by Wilcox et al is used. The day of ovulation is calculated by subtracting 14 days from the date of next period and depending on the day of coitus in relation of this day probability is estimated (fig. 1)

Thus efficacy of EC is expressed in two ways.

(1) Overall pregnancy rate and (2) Pregnancies prevented.


The main problem with hormonal pills is nausea and vomiting, which is comparatively more with Yuzpe method than LNG alone. To prevent these, it was advocated to prescribe these drugs with anti-emetics. But, currently, this is considered unnecessary. Mifepristone has fewer incidences of nausea and vomiting. The other common side-effect is on the menstrual cycle which may get pre-poned or post-poned. The amount of blood loss may also be more or less. Menstrual delay is seen more often following use of mifepristone.

No increase in the risk of thrombo-embolic disorders is observed.

Contra-Indications :

Pregnancy is the only contra-indication to use of EC.

Effect on pregnancy

Emergency contraception is capable of preventing 75-99% of pregnancies which would have occurred if no contraceptive was used. Thus 1-2% of women using these methods may conceive. It is desirable to have abortion facilities available for these patients. But, if a woman elects to continue the pregnancy, there is no direct detrimental effect of these methods on blastocyst and no increase in the risk of fetal malformations. There is no increase in the risk of ectopic pregnancy.

A comparison of different methods is presented in the table below.


The use of Emergency Contraception is required by women who experience unprotected sex for whatever reason. There is a short time-frame of efficacy for these methods (upto 120 hours). Once implantation has occurred, these methods are ineffective. EC is safe and effective averting 75-99% of expected pregnancies, thereby reducing the risks of undergoing an abortion or agony of carrying an unwanted pregnancy. It should be clear that EC is a one-time procedure. Regular use of effective contraception should be encouraged after onset of periods.

Table : Comparision of Methods for Emergency Contraception


Time Frame


Pregnancy Rate



No contraceptive method

(overall 8%)

Risk based on timing of IC

Vaginal douching




Very low efficacy

High dose estrogen

72 hours

DES 50mg x 5D
EE 5mg x 5D

0.3 – 1.6%

N = 50%
V = 25%

Failure to complete regimen

Yuzpe method

72 hours

2 tablets of 50µgEE
+ 0.25mg LNG
Repeat after12 hours

0.2 – 3.2%

N = 51
V = 19%

Risks of estrogen use
Low efficacy


72-120 hours

1 tablet of 0.75mg LNG
repeat after 12 hours
Single dose - 1.5mg


N = 23%
V = 6%

Safe and effective

Copper T

5-7 days

< 1%

Risk of PID
Unsuitable for nullipara

Continued contraception,
Further acts of IC protected
Infrastructure & training required



Single dose - 600 mg.


menstrual delay

High cost
Confusion with abortifacient
Risk of ectopic pregnancy



Single dose - 50 mg.


(36%) specially


Single dose - 10 mg.


with higher dose
N = 17%
V = 2%


72 hours

800 mg. x 3 doses
1200 mg. x 2 doses


Androgenic on repeated use



120 hours

50 mg. 2 tablets

to be evaluated

Menstrual delay

Controlled trials needed

N = nausea V = vomiting IC = Intercourse

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