Members Evidence Request - Supporting Clinical Practice

The Clinical Effectiveness Unit (CEU) provides an evidence-based enquiry service for FSRH members. The CEU will conduct a literature review and summarise the available evidence in relation to a particular medical condition and/or contraceptive method.

Recent Questions and Answers that have been submitted to the CEU can be seen below. Please note, the full answer includes references to more information and guidance.


To gain access to the members evidence request service, please log in to ‘My FSRH’ and click on ‘Members' evidence request’ to search for questions or submit your own question. This service is available to current FSRH members. If you are an FSRH member and have not yet created your ‘My FSRH’ account, please click the ‘Register’ button on the top right of this website and follow the steps to gain access to your account. View a video on how to register on our website here

Example Question One

A patient of mine wishes to switch from the pill to the Natural Fertility App because she read it’s more effective. What do I advise her?


Natural Cycles® is a mobile application that is certified in the EU as a contraceptive device. The app uses calendar tracking of menstrual cycles and basal body temperature (BBT) monitoring to determine - using the app’s algorithm - whether on a given day a woman is potentially fertile or is not fertile. On potentially fertile days, a woman must abstain from intercourse or use a barrier contraceptive to avoid pregnancy. On days identified as “not fertile” no additional contraception is required. There is an additional option for women to choose to purchase urinary LH tests and input LH data to the app.

The Natural Cycles website states that the app is not as effective as long-acting reversible contraceptive methods, but suggests that it offers a contraceptive option that is of similar effectiveness to oral contraception and more effective than condoms alone. The website advises that with perfect use of the app, 1 in 100 women will become pregnant in a year, either because the app wrongly categorised a fertile day as a “green” day or because the additional contraceptive method failed. With typical use over the course of a year, 7 in 100 women will become pregnant. 
To use the Natural Cycles app, a woman takes her temperature each morning using a specific thermometer provided by Natural Cycles  and inputs temperatures into the app along with information about when she menstruates, and, if she wishes, LH measurements. The app indicates each day whether she requires to use contraceptive protection on that day (a “red” day) or not (a “green” day). The number of “green” days may be small initially, but increases with time as the amount of recorded data increases. The manufacturer advises that if a woman has a reasonably regular cycle and inputs temperature data five or more times per week, she can expect about 60% of days to be “green” after three months of use.

BBT must be taken when the woman wakes in the morning, before she does anything else. BBT fluctuations can occur due to external factors such as illness, changes in sleep pattern, alcohol, other medications; such variation may result in more “red” days.

The Natural Cycles app is thus heavily user-dependent. It relies on a woman’s commitment to BBT monitoring, inputting data and abstaining or using a barrier method reliably when a “red” day is indicated. 

A study published in December 2017 (1) evaluated the contraceptive effectiveness of the Natural Cycles app. The study’s authors include the app’s developers. The prospective cohort study followed 22,785 paying users of the app and considered a total of 18,548 woman-years of app use. It reported 1,273 unplanned pregnancies. Method discontinuation was 54% at one year. 778 paying users inputted no data at all and 4,182 logged a total of fewer than 20 days of data. The perfect use failure rate was reported as 1% (95% CI 0.5-1.5) and typical use failure rate as 7% (95% CI 6.5-7.2). Perfect use data were taken from cycles in which users logged “protected intercourse” or “no intercourse” on all “red” days. All other use was considered typical use. The study has several limitations, including the following:

  • Recording of data was incomplete. For example, intercourse was not recorded in half of cycles in which pregnancy occurred. There could have been women using the application perfectly but not recording that they had done so; these data were included in typical use rather than perfect use statistics.
  • No data are available regarding use of emergency contraception following unprotected intercourse during the study.
  • The women in this study may have been “early-adopters” who had actively sought alternative contraception – a group of women who could potentially be more motivated to use this method and comply with its requirements than “typical users” of contraception.

Many established Fertility Awareness Methods (FAM) of contraception use BBT and calendar monitoring (sometimes along with other fertility indicators) to guide abstinence or use of barrier contraception. Natural Cycles app is distinguished from other FAM by its use of an electronic algorithm rather than relying on the woman’s own calculations. Some studies of existing FAM methods report good effectiveness. The FSRH CEU considers the Natural Cycles app to be a variation on other FAM methods and as such it depends heavily on user compliance and the reliability of alternative contraception during fertile days. 

As a FAM, the FSRH CEU considers that the Natural Cycles app could be a suitable contraceptive method for certain motivated users who understand the commitment involved and the limitations of the method. Further studies evaluating the effectiveness of the Natural Cycles app in typical populations are welcomed. Women should be aware that other apps that may appear to be similar do not have a European certification for contraception. Women wishing to avoid hormonal methods of contraception should be provided with information about copper intrauterine devices, as their failure rate is <1% with both perfect and typical use.

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Example Question Two

I have a lady with previous malignant germ cell tumour in 2006 who had salpingo-oophorectomy and chemotherapy. She was discharged from follow-up in 2011 and has had two subsequent deliveries. She tells me she was told to avoid hormonal contraception after her cancer. Is there evidence to support this advice?


Malignant ovarian germ cell tumours include dysgerminomas, immature teratomas, embryonal tumours and endodermal sinus (yolk sac) tumours. The FSRH CEU conducted a systematic literature review and did not identify any studies relating to the use of hormonal contraception following treatment for malignant germ cell tumour. Treatment of ovarian cancer has historically rendered a majority of women infertile. Perhaps as a result, no studies are identified that consider the impact of use of hormonal contraception after ovarian cancer on prognosis and risk of recurrence.

It is well documented that combined oral contraception reduces a woman’s risk of developing ovarian cancer. [1-4] Available evidence suggests that depot medroxyprogesterone acetate is not associated with an increased risk of developing ovarian cancer: some studies demonstrate a protective effect. [5-8]Most of the limited evidence relating to ovarian cancer risk with intrauterine contraception suggests no increase in risk. [9-12] However, this evidence cannot be extrapolated and applied to women who have had ovarian cancer. 

Depending on the hormone receptor status of ovarian tumours, gynaecological oncologists may advise against use of hormonal contraception after some types of ovarian cancer. The CEU advises, therefore, that the opinion of the woman’s gynaecology/ oncology team is sought with regard to use of hormonal contraception.

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Example Question Three

In the absence of other risk factors is it reasonable to prescribe the combined pill to a woman with Raynaud's disease. Intuitively there is some risk but I cannot see it in the UKMEC summary tables?


Raynaud’s Disease is characterised by exaggerated cold-induced vasoconstriction usually at the fingers and toes. 

It has been reported that estrogen increases expression of α2C adrenoceptors in vascular smooth muscle. These receptors mediate cold-induced vasoconstriction. This has been suggested as a mechanism by which estrogen (exogenous or endogenous) could be associated with risk of Raynaud’s. [1] 

The CEU conducted a systematic review of literature and did not identify any robust studies on use of contraception by women with Raynaud’s. There is a letter published in the BMJ in 1976 of 3 women with RP experiencing worsening of Raynaud’s symptoms with the use of combined oral contraceptives (COC) which improved when COC was stopped. [2]  

Primary Raynaud’s disease is not a contraindication to use of combined hormonal contraception. However Raynaud’s disease is often secondary to underlying medical conditions such as SLE or systemic sclerosis. Women with secondary Raynaud’s Disease may have underlying medical conditions (autoimmune e.g. SLE with positive antiphospholipid antibodies [APLA], vasculitis) in which use of CHC may be contraindicated.[3] One study of 940 women with systemic sclerosis found a positive association between APLA (specifically ACA-IgM) and Raynaud`s phenomenon (OR 2.39, 95% CI: 1.08-5.27, p=0.031). [4] The authors concluded that this association suggests that small vessel thrombosis and endothelial abnormalities may be associated with the pathogenesis of Raynaud’s.

It is not always apparent whether a women has primary or secondary Raynaud’s disease – an underlying condition may not be apparent. The rheumatologist we consulted during development of UKMEC 2016 [3] highlighted the importance of effective contraception for women with Raynaud’s given that the risks of pregnancy in diseases such as systemic sclerosis that are strongly associated with Raynaud’s disease can significantly outweigh any theoretical risk associated with contraception. However, contraceptive methods other than CHC (many of them more effective for contraception than CHC) are not associated with a significantly increased risk of thrombosis and the CEU recommends that these may be more appropriate contraceptive options.

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Please note: The advice given by the CEU should be considered as guidance only and is meant to be used alongside clinical judgement to guide clinical practice or policy. Questions that are a matter of clinical judgment and not evidence should be directed to local sexual and reproductive health leads.