Research on hormonal contraceptives is needed to monitor their evolving safety profile

Hormonal contraception has been a fundamental aspect of reproductive health for decades. It remains a crucial tool that enables women to make informed decisions about family planning. Given the extensive and ongoing reliance on these drugs, ensuring their safety remains a critical responsibility of the medical community.

Despite their longstanding presence on the market, hormonal contraceptives continue to evolve with new formulations featuring lower doses and diverse active ingredients. These innovations, although designed to improve tolerability and usability, necessitate continual evaluation. Sex hormones influence a wide array of tissues and physiological processes beyond reproduction, and it is essential to understand the intended and unintended effects of these medications. Ongoing research is critical to identifying potential risks, ensuring that the benefits of hormonal contraception continue to outweigh any associated harms.

In our latest nationwide study, published in The BMJ,1 we aim to deepen the understanding of how contemporary hormonal contraception use influences the development of stroke and myocardial infarction.

Although previous research has provided valuable insights, it is largely based on combined oral products and older formulations. This leaves gaps in knowledge regarding the risks associated with newer products, including insufficient information on the effects of mode of administration, oestrogen type, progestin type, and duration of use.2345

Our study included over two million women of reproductive age across more than 22 million person years. We observed an increased risk of first time arterial thrombotic events associated with the use of contemporary hormonal contraception.1 This included combined pills, progestin-only pills, combined vaginal ring, combined patches, and progestin-only subcutaneous implants. The hormonal intrauterine device (IUD) was not linked to an increased risk of stroke or myocardial infarction.1 The degree of risk varied among products, with the highest risks observed for combined oral contraceptives containing high dose ethinyl oestradiol and third or fourth generation progestins, as well as the combined vaginal ring and patch.1 Limited data resulted in uncertainty about the risks associated with progestin-only pills, implants, and injections.1

Leveraging the unique Danish nationwide registries, this study included all eligible women and adjusted for key factors, such as hypertension, hypercholesterolaemia, diabetes, atrial fibrillation, body mass index, smoking, and family history.1 By doing so, it provides critical insights into the potential effect of active ingredients, doses, and duration of use of hormonal contraception on arterial health. For women and healthcare providers, this offers a clearer understanding of how different hormonal contraceptive formulations may influence arterial health, allowing for more personalised risk-benefit assessments when choosing contraception. The key takeaway is that not all hormonal contraceptives carry the same risk of stroke and myocardial infarction, and individualised prescribing—considering factors such as dose, active ingredients, and patient-specific risk factors—may enhance safety in contraceptive choices.

Although the absolute increased risks of stroke and myocardial infarction with hormonal contraception use were low,1 reflecting the rarity of these conditions in young women, the findings are of substantial public interest. Hormonal contraception is widely used worldwide, and even a small increase in the risk of serious adverse events can have meaningful implications at a population level. Our findings underscore the critical need for continued research into the cardiovascular effects of hormonal contraception. Future studies should focus on identifying potential biological mechanisms underlying these risks, exploring how individual factors such as genetic predisposition, lifestyle, and comorbidities interact with contraceptive use.

We urge the medical and scientific communities to maintain a strong focus on this field. Hormonal contraception may be an old drug category, but its story is still unfolding. Continuous research ensures that we remain attuned to its evolving safety profile, safeguarding the health of millions of women worldwide.