Key questions on oral contraception (1.5 hours)

Dr Anne MacGregor answers GP Dr Pam Brown‘s questions on failure rates, interactions and how to advise women wanting to come off the Pill in order to conceive

1 What are the comparative failure rates at different ages for Cerazette and a 30µg combined oral contraceptive?

Desogestrel 75 (Cerazette) is an effective progestogen-only method of contraception. Unlike traditional progestogen-only pills – which act mainly to alter cervical mucous to prevent sperm penetration – the mode of action of Cerazette is to inhibit ovulation. This means it has comparative efficacy to low-dose combined oral contraceptives (COCs), which also inhibit ovulation.

Data from clinical trials suggest that the Pearl Index (number of pregnancies per 100 woman-years of use) for Cerazette is around 0.14. This is equivalent to the reported Pearl Index for low-dose combined oral contraceptives of 0.12-0.54.

There are no specific data on failure rates at different ages for Cerazette compared with COCs. But failure rates for Cerazette are likely to be similar to those with COCs, which decline from age 30 onwards.

2 What is the difference in failure rates between combined low-dose pills containing 20µg versus 30/35µg ethinylestradiol in women under 20 years? Is there a big difference in cycle control and is the side-effect profile much improved?

The EURAS trial assessed failure rates in age groups under-18s, 18-24, 25-29, 30-34, 35-39 and 40 or over.1 Data was analysed on 80,306 women on pills containing 30µg of ethinylestradiol or more and 19,492 women on pills with less than 30µg ethinylestradiol.

Age seemed to be a key factor. The highest rate of contraceptive failure was observed in the 18- to 24-year-old group, and a marked decline was observed in women over 29 years old. Dose appeared to have minimal effect on the rate of failure.

A recent Cochrane review suggests that women on 20µg ethinylestradiol pill have more bleeding problems than those taking pills with more oestrogen. But the authors noted that bleeding problems could be related to progestogen type as well as estrogen dose. Side-effects do appear to be dose-related, with bloating, nausea and breast tenderness about 50% more common in women using 35µg ethinylestradiol compared with 20µg preparations.

3 How does duration of oral contraceptive use influence fertility rates? What advice should we give women who are stopping the Pill because they want to conceive?

Duration of oral contraceptive use does not adversely affect fertility. One study found that women using the Pill for at least five years conceived faster than women who had never taken it. But most studies report a few months' delay in conception after oral contraceptive use compared with non-hormonal methods.

Women who stop the Pill to have a planned pregnancy are still generally advised to use another contraceptive method, such as condoms, until they have had one natural period – the one following the ‘withdrawal' bleeding from the last packet of pills. There are no medical concerns about pregnancy immediately after stopping the Pill but it is easier to ‘date' the start of the pregnancy from a natural period. Folic acid should be taken as soon as a woman plans to conceive.

4 How soon after delivery can a combined hormonal contraceptive (CHC) be started?

In non-breast-feeding women, the earliest date of ovulation is around day 28 postpartum. Given that the maximal survival of sperm is seven days, CHCs should be started on day 21 postpartum, without need for additional contraception.2 They should not be started earlier, due to the increased risk of thrombosis.

If an amenorrhoeic women starts CHCs after day 21, ensure she is not already pregnant or at risk of pregnancy, and advise her to avoid sex or use a barrier method for the first seven days. If her menstrual cycle has returned, she can start CHCs within five days after the start of bleeding with immediate contraceptive effect.

Breast-feeding women should avoid CHCs in the first six weeks postpartum as they may reduce milk production.3

In partially or token breast-feeding women beyond six weeks, the benefits of CHC use outweigh the risks.

Fully breast-feeding women may use the lactational amenorrhoea method (LAM). This is more than 98% effective in women who are below six months postpartum, amenorrhoeic (no bleeding after the first 56 days postpartum) and breast-feeding day and night.

From six months postpartum, CHCs can be used with the usual indications and contraindications.

5 How common is irregular bleeding in women taking progestogen-only pills? If this is troublesome is it worth changing to an alternative POP and if so are there recommendations for which to change to?

Studies show that irregular bleeding is a problem with desogestrel as well as with traditional levonorgestrel, norethisterone and etynodiol diacetate progestogen-only pills (POPs). In a study comparing desogestrel and levonorgestrel POPs,

45% of women in the desogestrel group and 39% in the levonorgestrel group stopped their pill, with about one-half from each group citing irregular vaginal bleeding as the reason.

Duration of use is important. In the first three months of use, desogestrel users are more likely to be amenorrhoeic or to have frequent or prolonged bleeding than women on levonorgestrel. About 50% of desogestrel users achieve amenorrhoea or infrequent bleeding with continued use, compared with 10% of levonorgestrel users.

There is no clear guidance on the effect of changing to a different POP, although in clinical practice it is worth switching to a preparation with a different progestogen, having considered other causes of bleeding such as STIs, cervical pathology and pregnancy. There are case reports of using two traditional POPs daily to control bleeding effectively – an unlicensed option.

6 Can progestogen-only emergency contraceptive pills be used in women taking liver-enzyme inducers. Is there specific advice for ulipristal?

CYP3A4 inducers – such as rifampicin, phenytoin, phenobarbital, carbamazepine, ritonavir and St John's wort – reduce plasma concentrations of levonorgestrel and ulipristal acetate, and may result in reduced efficacy.

So the best emergency contraceptive option for women taking liver enzyme inducers is a copper IUD, particularly if the woman may continue the IUD long term.

Otherwise, women using liver enzyme-inducing drugs should double the standard dose of levonorgestrel 1.5mg, taking a single unlicensed 3mg dose.

There is no guidance regarding ulipristal, which is not recommended for use in women who have taken enzyme-inducing drugs in the preceding two to three weeks.

7 What drugs interact with POPs, and how should we advise women on additional contraception when taking other drugs?

Liver enzyme-inducing drugs increase the metabolism of progestogen, potentially reducing the contraceptive efficacy of all types of POPs as well as Implanon. Women who take enzyme-inducing drugs long term should preferably use another method, such as Depo-Provera, or an IUD or IUS.

Women using liver enzyme-inducing drugs short term should use an additional method such as condoms during treatment – continuing for at least four weeks after the liver enzyme inducer is stopped.

Additional precautions are not necessary with non-enzyme inducing antibiotics as, in contrast to oestrogen-containing pills, the efficacy of progestogens is not affected.

8 Which women are not suitable for POPs? Would this apply to a one-off dose of emergency contraceptive as well?

POPs have very few absolute contraindications, but these are:

• any serious side-effect with a COC that was not clearly due to oestrogen – such as past liver tumour or allergy to progestogen

• current breast <|><<|>A<|> <|>H<|>R<|>E<|>F<|>=<|>"<|>h<|>t<|>t<|>p<|>:<|>/<|>/<|>w<|>w<|>w<|>.<|>p<|>u<|>l<|>s<|>e<|>t<|>o<|>d<|>a<|>y<|>.<|>c<|>o<|>.<|>u<|>k<|>/<|>i<|>n<|>d<|>e<|>x<|>.<|>a<|>s<|>p<|>?<|>n<|>a<|>v<|>c<|>o<|>d<|>e<|>=<|>9<|>9<|>6<|>"<|>><|>c<|>a<|>n<|>c<|>e<|>r<|><<|>/<|>A<|>><|>

• undiagnosed bleeding

• actual or possible pregnancy

• a condition that interferes with the POP being absorbed – such as Crohn's disease.

Use POPs with caution in women who:

• have had breast cancer that has been in remission for at least five years

• are taking enzyme-inducing medicine

• have new-onset stroke and ischaemic <|><<|>A<|> <|>T<|>A<|>R<|>G<|>E<|>T<|>=<|>"<|>_<|>B<|>L<|>A<|>N<|>K<|>"<|> <|>H<|>R<|>E<|>F<|>=<|>"<|>h<|>t<|>t<|>p<|>:<|>/<|>/<|>w<|>w<|>w<|>.<|>s<|>e<|>a<|>r<|>c<|>h<|>m<|>e<|>d<|>i<|>c<|>a<|>.<|>c<|>o<|>.<|>u<|>k<|>/<|>s<|>e<|>a<|>r<|>c<|>h<|>.<|>d<|>o<|>?<|>q<|>=<|>h<|>e<|>a<|>r<|>t<|>+<|>d<|>i<|>s<|>e<|>a<|>s<|>e<|>&<|>u<|>s<|>e<|>r<|>a<|>c<|>t<|>i<|>o<|>n<|>=<|>s<|>e<|>a<|>r<|>c<|>h<|>&<|>s<|>s<|>=<|>d<|>e<|>f<|>L<|>i<|>n<|>k<|>&<|>f<|>r<|>=<|>t<|>r<|>u<|>e<|>&<|>c<|>=<|>g<|>p<|>"<|>><|>h<|>e<|>a<|>r<|>t<|> <|>d<|>i<|>s<|>e<|>a<|>s<|>e<|><<|>/<|>A<|>><|> (current POP users)

• have liver damage with abnormal LFTs.4

POPs are particularly suited to:

• breast-feeding women

• women who have risk factors that rule out, or lead to side-effects with, oestrogen-containing methods

• women who have migraine with aura

• women who have blood-pressure problems on the COC pill

• women with <|><<|>A<|> <|>T<|>A<|>R<|>G<|>E<|>T<|>=<|>"<|>_<|>B<|>L<|>A<|>N<|>K<|>"<|> <|>H<|>R<|>E<|>F<|>=<|>"<|>h<|>t<|>t<|>p<|>:<|>/<|>/<|>w<|>w<|>w<|>.<|>s<|>e<|>a<|>r<|>c<|>h<|>m<|>e<|>d<|>i<|>c<|>a<|>.<|>c<|>o<|>.<|>u<|>k<|>/<|>s<|>e<|>a<|>r<|>c<|>h<|>.<|>d<|>o<|>?<|>q<|>=<|>d<|>i<|>a<|>b<|>e<|>t<|>e<|>s<|>&<|>u<|>s<|>e<|>r<|>a<|>c<|>t<|>i<|>o<|>n<|>=<|>s<|>e<|>a<|>r<|>c<|>h<|>&<|>s<|>s<|>=<|>d<|>e<|>f<|>L<|>i<|>n<|>k<|>&<|>f<|>r<|>=<|>t<|>r<|>u<|>e<|>&<|>c<|>=<|>g<|>p<|>"<|>><|>d<|>i<|>a<|>b<|>e<|>t<|>e<|>s<|><<|>/<|>A<|>><|>

• women with a BMI over 30 – especially BMI of 40 or more (best choice is Cerazette)

• smokers, especially over age 35

• other older women, especially non-smokers around the menopause.

There are no contraindications to the use of progestogens in emergency contraception, even when there are contraindications to long-term use.

9 What are the pros and cons of using the contraceptive patch compared with combined oral pills?

The pros are:

• both methods are highly effective when used correctly

• both are independent of intercourse

• both have minimal side-effects

• both are reversible

• with patches, there is no need to remember to take a pill every day as they are replaced weekly.

The cons are:

• neither method protects against STIs

• patches are more expensive than pills

• increased oestrogen exposure with patches may cause other problems

• initial side-effects such as breast tenderness may be more common with patches than pills

• skin irritation can occur with patches

• patches are visible contraception

• patches may not stick, particularly if bath oils or body lotions are used.

10 Are there new oral contraceptive pills in development and what advantages will they have over current contraceptive pills?

The major developments aim to reduce the number of pill-free days, reduce the dose of ethinylestradiol and use natural, rather than synthetic, oestrogen.

Shortening or removing the hormone-free interval has the potential to increase efficacy and reduce withdrawal symptoms. The disadvantage is unscheduled bleeding, although this usually resolves with continued use.

The following new products have been launched elsewhere but unfortunately not in the UK, as yet:

• a low-dose pill containing 20µg ethinylestradiol and 90µg levonorgestrel, to be taken every day without a break

• long-cycle regimes of 84 days of combined pills followed by either seven hormone-free days or seven days of 10µg ethinylestradiol

• 15 or 20µg ethinylestradiol pills for 24 days, followed by either four days of placebo or four days of ferrous fumarate tablets

• 20µg ethinylestradiol taken for 21 days followed by two placebos and five days of 10µg ethinylestradiol

• a chewable spearmint-flavoured pill is also available, to be chewed or swallowed with seven days of 75mg ferrous fumarate daily in the hormone-free interval.

11 How does the failure rate of POPs differ in women who are breast-feeding to those who are not?

Women who are fully breast-feeding, who are less than six months postpartum, and who are amenorrhoeic do not need additional contraception since lactational amenorrhoea is more than 98% effective in preventing pregnancy. Once menstruation has resumed, lactation no longer reliably inhibits ovulation, even if the woman continues to breast-feed.

POPs have minimal effect on the quantity or quality of breast milk and are the contraceptive of choice for women who are not fully breast-feeding. Breast-feeding in combination with the traditional POPs (pills containing levonorgestrel, norethisterone and etynodiol diacetate) is likely to provide equivalent efficacy to non-breast-feeding women taking CHCs or desogestrel, which inhibit ovulation.

The POP can be started at any time postpartum. If started after day 21, the Clinical Effectiveness Unit of the Faculty of Sexual and Reproductive Healthcare advises additional contraception for the first 48 hours, although the Summaries of Product Characteristics (SPCs) for POPs suggest seven days.3

Dr Anne MacGregor is associate specialist in sexual and reproductive healthcare at Barts Sexual Health Centre, St Bartholomew's Hospital, London

Dr MacGregor is co-author of The Pill and other forms of hormonal contraception: The Facts (seventh edition 2009)

Dr Pam Brown is a GP in Swansea

Competing interests: none declared

Fill in our short survey about how you plan to collect your 50 CPD credits and we will automatically enter you into a prize draw to win a Bose docking station and an 8GB iPod touch worth £350!

Please click here to complete the survey.

Click here to take the CPD assessment