People requesting abortions in England and Wales have been using less reliable contraception methods in the past decade, according to a new study.

The report also shows a large increase in those using no contraception.

The research, published in BMJ Sexual & Reproductive Health, finds that fewer abortion patients are using reliable hormonal contraceptive methods, like pills or implants, while more are using less reliable “natural” methods like fertility tracking.

The research didn’t investigate why these trends are happening. The researchers say it could reflect a change in people’s preferences, or it could be caused by difficulties accessing more effective contraception.

Abortion rates have been increasing across the UK in recent years.

“The reasons for this are likely multifactorial,” write the researchers in their paper.

“However, greater use of less-effective methods could lead to a higher rate of unintended pregnancy and demand for abortion.”

There isn’t much robust data on contraception trends, according to the researchers.

Fertility awareness-based contraception uses various tools, like calendars, apps, or symptom tracking, to avoid unprotected sex at points in the menstrual cycle where conception is likely. It’s generally less effective than hormonal or medical contraception, with the World Health Organization saying that it fails for between 2 and 23 people out of 100 in the first year of use.

While “traditional” fertility awareness methods have been used for centuries, fertility and period-tracking apps have increased in popularity over the 2010s and 2020s.

At the same time the oral contraceptive pill has dropped in use in the UK. The researchers say that in the UK and Europe, anecdotal and qualitative evidence suggests that young women are more reluctant to use hormonal contraceptive methods – including the pill, injections, patches, and vaginal rings.

In Australia, one study found that young women were increasingly using long-acting reversible contraception (LARCs), such as intra-uterine devices (IUDs) and implants, which are the most effective methods.

The researchers examined data from the independent healthcare charity British Pregnancy Advisory Service (BPAS) from the first half of 2018 and the first half of 2023.

They examined the self-reported contraception use among patients presenting for abortion – a total of 33,495 people in 2018 and 55,055 people in 2023. The researchers point out that in this period, the BPAS increased the total proportion of abortions it performed, while other organisations in the UK lowered their share of abortion care.

They found fertility awareness-based methods increased in use from 0.4% in 2018 to 2.5% in 2023. The specific type of fertility awareness wasn’t recorded, so they can’t glean how much of this was from apps or other new technology.

Hormonal contraception, meanwhile, dropped from 18.8% of the 2018 cohort to 11.3% of the 2023 cohort. LARC use fell from 3% to 0.6%.

There was a large increase in those using no contraception: from 55.8% in 2018 to 69.6% in 2023.

These trends mirror a decrease in access to more effective contraception, after COVID-19 forced changes in the healthcare system, say the researchers.

“The amalgamation of a shift in attitudes and difficulty in accessing certain methods have led to increasing use of less reliable methods, which in turn has a potential to increase unintended pregnancies,” they write.

They also say that the rising popularity of fertility apps “needs scrutiny”.

“The possible relationship between these less effective methods of contraception and unplanned pregnancy requires further investigation,” they write.

The researchers point out that the cohort of people seeking abortions is not the same as the cohort of sexually active people, so this study may not reflect whole-population trends.

Also, in this time period, abortion care access changed in the UK, with telephone consultations becoming more common, and fewer in-person visits required. This might have influenced the information patients gave about their contraceptive methods.

The researchers call for further research to understand why these changes have happened.