Some women are concerned about how contraceptive pills could be affecting their mental health. Are these fears backed up by evidence?

Like many young women, Sarah E Hill spent her late teens and most of her twenties on the contraceptive pill. "I never thought twice about it," says Hill, now a researcher who teaches evolutionary psychology at Texas Christian University, an institution affiliated with the Christian Church (Disciples of Christ) in the United States. It was only when she switched contraceptives, 12 years after starting to take the pill, that an epiphany dawned on her.

"My life felt brighter and more interesting, like I had walked out of a 2D black-and-white movie into a full-colour, 3D, meaning-filled reality," says Hill. Her experiences of taking oral contraceptives inspired her to study the science involved and publish a book, How the Pill Changes Everything, in 2019.

In recent years, many women have become concerned about the pill's side effects, particularly on their moods and mental health. In fact, there has been a growing backlash – one which is most evident on social media where hashtags like #quittingbirthcontrol have drummed up millions of views. This is thought to partly explain why the pill has been suffering a popularity crisis of late.

Prescription figures are falling in many developed countries: England's Sexual and Reproductive Health services reported that the uptake of oral contraceptives had fallen from 39% in 2020-2021 to 27% in 2021-2022. Meanwhile, American pill-users dropped from 31% in 2002 to 24% between 2017 and 2019, while Canada and Australia reported pill use tailing off from 23% to 11% from 2006-2016 and 2008-2016, respectively.

In addition to discussing legitimate concerns, social media influencers have been spreading misinformation about the contraceptive pill's side effects, both mental and physical. While they may have no medical background, some are even encouraging women to abandon contraception altogether – a trend which some experts believe could be behind a recent spike in abortions in the UK.

But can the pill really alter one's personality and outlook on life? Can it contribute to serious mental health conditions such as anxiety and depression, or even lead to suicide, in extreme cases?

The answer, it appears, isn't clear-cut.

When the pill made its debut in the US in 1960, it amassed a whopping 1.2 million users within two years. The tiny beige tablets marked a revolutionary new birth control, hailed by women as a symbol of sexual liberation and female empowerment, freeing them from fear that an unwanted pregnancy would derail their careers or degrees.

Today, oral contraceptives are the go-to choice for some 150 million women around the world, or roughly 16% of the global contraceptive-taking population, with a failure rate of only 1% (or 9% when you factor in human error such as forgetting the occasional dose). The failure rate of a contraceptive is defined as the number of unintended pregnancies that would occur if 100 women used that method for a year.

There are two types of contraceptive pill, and both are made up of artificial sex hormones. First, there's the most popular kind, the combined pill, which contains synthetic versions of oestrogen and progesterone. The other is the progestogen-only pill, or "mini-pill". Both work to prevent pregnancy in a handful of ways, including suppressing ovulation and thickening the cervical mucus to make it harder for a sperm to penetrate and reach an egg.

However, the hormones in oral contraceptives don't just affect the body, they can also have powerful effects on women's brains.

"The impact of hormones on the brain is complicated," says Johannes Bitzer, an obstetrician-gynaecologist (OBGYN) and psychotherapist at the University Hospital Basel in Switzerland. "For some individuals, the pill has a positive effect on mental well-being. In others, it may cause irritation and even anxiety."

Medical warnings, for the most part of the pill's 65-year history, have been scant. Some sexual health providers in the UK and the US make no mention whatsoever of the mental side effects of the pill on their websites.

"I think the big issue is that in OBGYN training, mental health is not a subject. It's for the psychiatrists," says Bitzer, who has been in the field for nearly 40 years. Things are slowly changing, but "before, when we discussed the pill, we talked about thrombosis, cancer, irregular bleeding, weight gain, and so on. The issue of mental health was more or less excluded," he says.

There hadn't been much........

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