The pill’s arrival in Britain in 1961 gave women sexual choice they could never have dreamed of and it remains the most widely-used contraceptive, with more than three million women in Britain taking it each year.

But could its popularity be waning? A new BBC documentary has looked into the side effects reported by women, asking whether the benefits outweigh the risks.

In a survey of more than 1,000 women conducted alongside the programme, more than half (52 per cent), reported side effects, ranging from weight gain to mental health problems. Should we be worried?

Historical studies into the pill have flagged contradictory results and subsequent newspaper headlines haven’t always been accurate. In a quest for answers, GP Dr Zoe Williams spoke to some of the world’s leading experts and looked at the most detailed current evidence available.

Here are five common questions and concerns answered in the show:

How Does The Pill Work?

In the BBC survey of more than 1,000 women aged 18-45, 66 per cent said they knew very little about what the hormones in the pill do to them.

So first thing’s first: there are two different types of pill, the combined pill and the progestogen-only pill.

In simple terms, both work by replacing a woman’s naturally occurring hormones with a steady stream of synthetic hormones. In a natural cycle, an egg is released from the ovaries every month. Both pills prevent the release of this egg – the main difference is you’ll usually take the combined pill for 21 days with a 7 day break, whereas the progestogen-only pill is taken every day. 

There are many different brands and variations of both types of pill, and it can sometimes be a case of trial and error to find the right one for you. And like all medication, the pill can cause side effects. 

Does The Pill Cause Breast Cancer?

More than a third of women surveyed said they worry the pill will give them cancer. 

Professor Philip Hannaford, an expert in hormonal contraception, made headlines when his large-scale study found women taking the pill have a 20 per cent increased risk of breast cancer compared to women who don’t.

During the show, Prof Hannaford cautioned that many of the reports were exaggerated because the the overall risk is still very low. He said that among 100,000 women who don’t take the pill, there would be 55 cases of breast cancer in a year. Among 100,000 women who do take the pill, after a year you’d find 68 cases of breast cases – that’s 13 extra cases per 100,000 women.

So the increase is small and your increased risk of breast cancer has been shown to decrease again within 5-10 years of stopping taking the pill. 

The pill has also been linked to a reduced risk of other types of cancer, Prof Hannaford said, including ovarian and endometrial cancer, but the research is not yet clear on why this is the case.

Does The Pill Give You Blood Clots?

Almost half (48 per cent) of women surveyed said they worried about blood clots in relation to the pill. 

“The combined oral contraceptive pill effectively gives a higher does of the female sex hormones and different types of hormones, which can result in an activation in the blood clotting system,” Professor Roopen Arya, from Kings College Hospital, explained. But again, the risk is small.  

Among 100,000 women not taking the pill, 20 will get a blood clot in the space of a year. The blood clot risk then differs depending on what pill you’re taking.

Pills called “second generation pills, which first came in during the 1970s, such as the commonly used Microgynon, have a 50-70 women per 100,000 blood clot risk. However, other newer “third generation” pills have a 90-120 women per 100,000 blood clot risk. 

It may sound high, but to put it into context, the risk of getting a blood clot while pregnant is actually higher, at 290 per 100,000 women. And in the few weeks after giving birth, this increases to 4,000 per 100,000. Essentially, staying on the pill (and not getting pregnant) is best.

Doctors can also identify which women are at higher risk of blood clots by asking a few simple questions, then offering them alternative contraception.  

Does The Pill Impact Mental Health? 

One quarter (25 per cent) of the women surveyed said they felt the pill had negatively affected their mental health and multiple women have previously shared their experiences of this with HuffPost UK. 

In Denmark, every citizen is given a medical pin number at birth and this pin number is then used each time they access medication, including the pill and antidepressants. 

Professor Oejvind Lidegaard from the university of Copenhagen analysed this data, and found people who took the pill had a 70 per cent higher instance of being prescribed anti-depressants, compared to non-pill users, 

Although we know there’s a correlation, we still can’t say for certain that the pill causes mental health problems until more research is conducted. So the current advice is to speak to your GP and consider changing your pill if you think you’re affected. 

Does The Pill Affect Your Sex Drive?

During the programme, Dr Cynthia Graham said there’s been “shockingly little research” into how the pill affects sex drive, despite many women reporting this anecdotally. 

She explained that studies in men have linked high levels to testosterone to high sex drive, and we know that levels of testosterone can be four times lower for women who take the pill compared to women who do not. Therefore, it’s completely feasible that the pill could lower sex drives for some women. 

Again, if you think you’re suffering negatively, switching your pill or using alternative contraception may help. 

‘BBC Horizon: The Contraceptive Pill: How Safe is It?’ is on BBC 2, Wednesday 21 November at 9pm.