Medication Safety in Women and the Burden of Contraindicated Medicines

Medication safety in women of reproductive age remains one of the most complex and underrecognised challenges in modern pharmacovigilance. Researchers traditionally focus much attention on drug use during confirmed pregnancy. However, emerging evidence shows that the real risk window often begins much earlier, before clinicians detect pregnancy.

Clinicians often rely on pharmacotherapy to manage chronic conditions, and many women cannot simply pause treatment due to the potential for pregnancy. However, several medicinal products can cause teratogenic effects or adverse pregnancy outcomes, creating a persistent tension between therapeutic necessity and safety.

A substantial proportion of pregnancies occur unplanned, which further amplifies this challenge. This reality shifts responsibility for risk mitigation from obstetric care to general prescribing practices across all healthcare settings.

The Critical Window of Risk

The period of organogenesis typically occurs between the fourth and tenth weeks of gestation. This phase represents the most sensitive time for drug-induced congenital malformations. During this time, exposure to certain medications can lead to irreversible developmental abnormalities.

What makes this particularly concerning from a pharmacovigilance perspective is that many women are unaware of their pregnancy during this early stage. As a result, exposure to potentially harmful medications may occur unintentionally, even when both patients and healthcare professionals act in good faith.

This creates a systemic vulnerability where traditional safety measures, often triggered only after pregnancy confirmation, may come too late to prevent harm.

Reframing Risk: Beyond Pregnancy

Unplanned pregnancies are highly prevalent. Therefore, the concept of medication safety must extend beyond pregnant populations to include all women of reproductive age. In practice, this means that any prescription issued to a woman between the ages of 15 and 49 carries an implicit, albeit variable, probability of early pregnancy exposure.

Certain medications, such as valproic acid, have long been recognised for their significant teratogenic risk. Regulatory agencies have introduced strict measures, including pregnancy-prevention programs and enhanced labelling requirements. Despite these efforts, real-world data consistently demonstrate ongoing use in populations where exposure remains possible.

This discrepancy between regulatory intent and clinical reality highlights a critical gap in the effectiveness of risk minimisation.

Medication Safety in Women Revealed Through Real-World Data

A recent retrospective descriptive study discovered by the DrugCard platform in the literature provides valuable insights into prescribing patterns among women of reproductive age. The analysis utilised data from Japan’s National Database of Health Insurance Claims and focused on outpatient prescriptions for oral medications dispensed to women aged 15 to 49 years.

The findings reveal a broad landscape of potential exposure. A total of 270 medicinal products were identified as contraindicated during pregnancy. Among these, 75 were also contraindicated for women planning pregnancy, indicating an overlap between preconception and gestational risk categories. Additionally, 58 active substances were restricted across both phases. One of the most notable observations is that 212 medications were contraindicated exclusively during pregnancy. This suggests that fetal development introduces additional layers of vulnerability beyond preconception considerations.

Despite these contraindications, commonly prescribed medications such as loxoprofen sodium hydrate, sodium valproate, and metformin hydrochloride were frequently dispensed within this population.

Understanding the Context of Exposure

Interpreting these findings requires careful consideration. The majority of women in this demographic are neither pregnant nor actively attempting to conceive. Therefore, the observed prescribing patterns largely represent standard clinical practice rather than inappropriate or unsafe behaviour.

However, from a pharmacovigilance perspective, this does not eliminate risk. Instead, it highlights a population-level exposure that persists continuously and may translate into adverse outcomes when it intersects with an unrecognised pregnancy. This creates a paradox where appropriate prescribing at the individual level can still contribute to preventable harm at the population level.

Implications for Pharmacovigilance Systems

The findings underscore the need for a more proactive and integrated approach to risk management. Pharmacovigilance systems must evolve beyond passive monitoring of adverse events toward anticipatory strategies that address exposure before it occurs.

This includes embedding pregnancy risk considerations into routine clinical workflows, rather than treating them as exceptional cases. Decision-support tools can play a significant role by alerting prescribers and pharmacists to potential risks at the point of care.

Equally important is the continuous analysis of real-world data to identify patterns of exposure and evaluate the effectiveness of existing risk minimisation measures. Without such feedback mechanisms, regulatory actions may fail to translate into meaningful changes in clinical practice.

Medication Safety in Women and the Role of Pharmacists in Risk Prevention

Pharmacists occupy a unique position within the healthcare system as the final checkpoint before medication reaches the patient. This places them at the forefront of preventing unintended exposure to contraindicated medicines.

Routine confirmation of pregnancy status, while seemingly straightforward, represents a powerful intervention. It transforms the dispensing process into an active safety measure that can identify risks that may not have been addressed earlier in the care pathway.

In this context, pharmacists function not only as dispensers of medication but as critical contributors to pharmacovigilance and patient safety.

Bridging the Gap Between Policy and Practice

One of the key challenges highlighted by these findings is the gap between regulatory frameworks and real-world implementation. Guidelines and restrictions play an essential role, but their effectiveness ultimately depends on how clinicians apply them in everyday clinical settings.

Bridging this gap requires a combination of education, system-level interventions, and cultural change within healthcare. Clinicians need the knowledge and tools to incorporate pregnancy risk into routine decision-making. At the same time, healthcare providers should encourage patients to discuss medication safety and reproductive health.

Conclusion

Medication safety in women of reproductive age represents a complex and dynamic challenge that extends beyond the boundaries of pregnancy itself. The evidence suggests that exposure to contraindicated medications is not uncommon. Instead, it represents an inherent feature of current prescribing practices.

For pharmacovigilance professionals, this shifts the focus from reactive detection to proactive prevention. The goal is not to eliminate necessary treatments but to ensure that clinicians anticipate, communicate, and manage risks effectively.

Ultimately, improving outcomes in this area will require coordinated efforts across the healthcare system, with pharmacovigilance playing a central role in guiding and evaluating these interventions.