Last month, the UK’s Faculty of Sexual and Reproductive Healthcare announced updated guidelines on oral contraceptives, declaring a seven-day break each month to bleed unnecessary. This prompted many women to voice their anger at having been seemingly hoodwinked by ill-advised or ignorant doctors – as well as to wonder what other misinformation about the pill women may have been given in the past 60 years.

Let’s look into the mythology surrounding the pill by answering these common questions.

Why is a break week included in pill packets?

Pharmaceutical companies have usually provided either just 21 pills or seven inactive pills in each monthly packet since the contraceptive first became available. Lisa Hendrickson-Jack describes the reason behind this in her book The Fifth Vital Sign: “The women who participated in the first round of testing for the very first pill, Enovid, stopped getting their periods, and quickly became convinced they were pregnant. They were devastated when they learned the truth – that the pill stopped them from having periods. It was at this point that the creators of the first pill added in a withdrawal bleed.” The idea was that if the pill mimicked the natural cycle, it would encourage more women to use it.

While these so-called “pill bleeds” have always been referred to as “periods” by most medical professionals, they bear no physiological or medical resemblance to menstruation. Women in the 1960s, just like women now, mistakenly believed this withdrawal bleed indicated the absence of pregnancy, and therefore the efficacy of the pill. In fact, you can have a withdrawal bleed and still be pregnant.

Will taking the pill regulate my cycle?

Almost one in three women are reported to be taking the pill on the advice that it will regulate their periods. Again, the bleeds you experience on the pill are not menstruation. The fluctuating hormones, ovulation and menstruation that make up your menstrual cycle are suppressed and replaced by a steady, consistent stream of synthetic hormones (synthetic oestrogen and progestin). The bleeds indicate your body’s response to the withdrawal of these synthetic hormones – a small amount of uterine lining builds up and then comes away. Some women may not experience a bleed at all, or only spotting.

Does the pill affect mood?

Women may have been assured by their doctor that the pill does not affect their mood – or has a positive impact, by preventing symptoms of premenstrual syndrome. In fact, in recent years, two large-scale studies from the University of Copenhagen have revealed that, for users of the combined pill, the likelihood of a diagnosis of depression is increased (by 23%) and, for users of all hormonal contraceptive types, risk of suicide is increased threefold. These studies revealed that for teenagers, clinical depression diagnosis is 80% higher and suicide risk doubles after just one year of use. These conclusions have not yet found their way into doctors’ practices, although the researchers argue that women should be warned of the possibility of these side-effects.

Does the pill cause cancer?

In her book Beyond the Pill, Dr Jolene Brighten examines the research connecting pill use to cancer diagnosis, concluding: “Breast, cervical, liver and brain cancer risks all increase with the pill. Incidences of uterine, endometrial, ovarian and colorectal cancers are reduced in women who take the pill. I would argue that there are far better ways to prevent cancer that can benefit your entire body and come with much fewer side-effects.” Looking at only the two most common female cancer types, for women who use the pill for a decade or more, a systematic review of 28 scientific studies revealed that the risk of cervical cancer doubles; and a study of 1.8 million women revealed that the risk of breast cancer increases by 38%.

What is the risk for blood clots?

Newer combined oral contraceptives, as well as synthetic-hormone-based devices such as the ring, have a higher risk of blood clots – and the consequent serious or even fatal complications – than older combined oral contraceptives. You may already know that you are at elevated risk on any pill if you are overweight, over 35 or if you smoke – but you are also at far higher risk if you have factor V Leiden, an inherited blood clotting disorder that is considered very common. The risk of death due to blood clots is one in 12,000 for women on the pill, compared with one in 50,000 for non-users – and the risk of hospitalisation is one in 2,000, compared with one in 20,000. As David Rowan details in My Beautiful Memory, a memoir of the death of his daughter, by pharmaceutical companies’ own estimates, this equates to the deaths of about 1,000 women a year in the US alone; it would be approximately 250 women a year in the UK. By comparison, about 250 people have died worldwide taking selfies, and it has made headlines.

Is being on the pill like being pregnant?

Women are told the pill “tricks” the body into thinking it is pregnant, and that side-effects (such as weight gain) are similar to those experienced during pregnancy. Lara Briden, author of Period Repair Manual, clarifies: “The pill is not like pregnancy for the simple reason that contraceptive drugs are not pregnancy hormones. In fact, the state of being on the pill is more like a temporary, chemically induced menopause in which hormones are suppressed and replaced with contraceptive drugs that have vastly different effects compared with our own human hormones.”

Does the pill affect fertility?

We understand the pill to be a reversible method of contraception – and it is commonly believed that fertility returns rapidly post-pill. However, while some women conceive rapidly post-pill, intentionally or unintentionally, others do not. This can depend on prior reproductive health issues, such as polycystic ovary syndrome, which will return once the pill is stopped.

Maisie Hill, a women’s health practitioner and the author of the forthcoming Period Power, says: “We know from research that women on the pill experience a reduction in ovarian volume and production of AMH – a hormone that’s tested to assess fertility – whilst they’re taking it, so it can take a while for the ovaries to regain function.” There is, she says, “an association between long-term pill use and a thin uterine lining, which is important, because a suboptimal endometrial thickness has a negative impact on your ability to conceive. The pill reduces absorption of vitamins and minerals that are essential for regular ovulation, as well as conceiving and sustaining a pregnancy.”

Does the pill make you gain weight?

The correlation between some hormonal contraceptives and weight gain is proven, with the contraceptive injection showing a significant effect; however, the research is conflicting when it comes to the pill. Many women do report gaining weight on the pill, and doctors are actively encouraged to quash such concerns to promote continued pill use. Other known side-effects such as depression may contribute to weight gain.

Did I break up with my boyfriend because of the pill?

Women often report feeling a change in attraction to their partner if they go on or off the pill during the course of a relationship. The experience is so widespread that Dr Julie Holland, in her book Moody Bitches, says she recommends that her patients stop taking the pill at least six months before their wedding day. Dr Sarah E Hill, a professor of psychology and author of the forthcoming book This Is Your Brain on Birth Control, agrees there might be a connection: “There is research that finds that going off the pill, if women chose their partners when on it, can lead to undesirable changes in relationship satisfaction. However, a recent attempt to replicate this result failed to find this pattern. The pill may influence women’s relationships with men (and there’s every reason to expect that it will, when we consider the way that sex hormones work), but we need more research to understand the conditions in which this does and does not happen.”

• Holly Grigg-Spall is a womens’ health activist and author of Sweetening the Pill:Or How We Got Hooked On Hormonal Birth Control.

• This article was amended on 25 February 2019 to clarify that a study of 1.8 million women revealed that the risk of breast cancer increased by 38%, not that there was an overall risk of 38%.