The Oral Contraceptive Pill

The oral contraceptive pill (‘the pill’) was introduced in May 1950. Initially marketed as a way of regulating the menstrual cycle, it contained artificial versions of the two female sex hormones, oestrogen and progesterone. These synthetic hormones were designed to mimic the activities of their endogenous counterparts. However, unlike the naturally-occurring hormones, there was no cyclical change in their levels throughout the menstrual cycle, meaning there was no trigger for the ovaries to release an egg and thus ovulation was impeded. Without ovulation, fertilisation could not occur.

The composition of the pill has changed since its early incarnation. The first pill contained 9.85mg progestin (synthetic version of progesterone) and 150µg oestrogen, today’s choice of pills are more likely to contain in the region of 0.1-3mg progestin and 20-50µg oestrogen. The refining of the component parts has made the pills in use today far more pharmacologically specific and safer. Using less than 50µg oestrogen means that there is no increased risk of stroke.

The development of the pill meant that, for the first time, women were able to take control of their own fertility and plan their families. However, its usage over the past 70 years has been marred by controversy, falsified claims and rumour-mongering, meaning that even today people are unsure whether the pill is to be celebrated or vilified.


In addition to preventing unplanned pregnancies, the pill has several non-contraceptive hormonal benefits. It is used to treat painful heavy periods and is often prescribed for those with PCOS, as well as managing the unwanted symptoms of the perimenopause, including hot flushes and irregular periods. It also reduces the negative side effects of premenstrual syndrome, such as mood swings and cramps. For women experiencing debilitating heavy bleeding, the pill can reduce this, significantly improving the quality of life and reducing hysterectomy rates. This makes it a valuable tool for managing the symptoms of endometriosis in those women who do not wish to conceive.

It has also been shown to protect against both ovarian cancer (relative risk reduced by 20% for each five years of use) and endometrial cancer (risk reduction of 50%, regardless of duration of use).

It protects against unplanned pregnancy, which is generally considered to carry more risks, physically and emotionally, than contraceptive use.


A lot of the negative press related to the pill has come from the identification of adverse side effects. The pill is said to increase the risk of venous thromboembolism (blood clots). In fact, for non-smokers the risk of developing a blood clot if they take the pill is 9.1 in 10,000. In contrast, the risk of developing a blood clot during a normal, otherwise healthy pregnancy is 30 in 10,000. That said, an element of caution is recommended, and those with a family history of thrombosis or blood clots should choose an alternative to the pill when considering contraception. Doctors will also exert caution when prescribing the pill to women who smoke and are over 35 years old, due to an increased risk of heart attack. The combined pill is also not recommended for those who suffer from migraines with an aura. This highlights the need for a doctor to take a detailed medical history of each patient prior to selecting a form of contraception.

The pill has been linked to an increased risk of breast, cervical and liver cancer. However, the data is limited and any associated risk disappears five to ten years after treatment ceases. To put it into context, the pill is thought to be implicated in less than 1% of breast cancer cases, with many studies finding that pill use does not increase breast cancer risk at all.

As previously mentioned, the pill can be used to treat conditions with hormonal elements, including endometriosis and PCOS. However, in the case of PCOS, its likely benefits are dubious. PCOS is often strongly associated with increased insulin resistance and as many forms of the pill impair insulin sensitivity, for these patients it is not an ideal treatment option. This does not mean it is not regularly prescribed, but does mean you should consider whether it is the best treatment option for you. Discuss the pros and cons with your doctor before starting any medication.

Another factor to consider is that the pill is not regulating the menstrual cycle; the monthly bleeds are not genuine periods, they are withdrawal bleeds. If your periods were irregular before you started taking the pill, once you stop taking it you are likely to revert to a similar state.
The final thing to note is that once you stop taking the pill, it can take months, or in rare cases years, for your menstrual cycle to become regular again.

The pill has a complicated history, but with an effectiveness of 92% (99% if taken correctly and consistently), it is still the contraceptive of choice for many women.

The pill has given rise to alternative hormonal contraceptive devices, including the progesterone-only ‘mini pill’, implants, intrauterine devices and injectables, giving women more options than they have ever had before for managing their fertility. However, all of these options involve hormonal regulation, usually with synthetic products, which means that even now, in the 21st century, women’s bodies are still being manipulated to control fertility.

Nabta is reshaping women’s healthcare. We support women with their personal health journeys, from everyday wellbeing to the uniquely female experiences of fertility, pregnancy, and menopause

Get in touch if you have any questions about this article or any aspect of women’s health. We’re here for you.


  • Cibula, D, et al. “Hormonal Contraception and Risk of Cancer.” Human Reproduction Update, vol. 16, no. 6, 2010, pp. 631–650., doi:10.1093/humupd/dmq022.
  • Liao, P V, and J Dollin. “Half a Century of the Oral Contraceptive Pill: Historical Review and View to the Future.” Canadian Family Physician, vol. 58, no. 12, Dec. 2012, pp. e757–760.
  • Trussell, J, and B Jordan. “Reproductive Health Risks in Perspective.” Contraception, vol. 73, no. 5, May 2006, pp. 437–439., doi:10.1016/j.contraception.2006.01.008.
  • “Combined Pill.” NHS, Page last reviewed: 06/07/2017.
  • World Health Organisation [website] Family planning. Fact sheet no. 351. July 2012. Available from: Accessed 15th April 2019.
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