Pregnancy Pharmacovigilance: gathering evidence for medicine safety in pregnancy

In addition to providing information and advice for women and healthcare professionals, the UK Teratology Information Service (UKTIS) plays a role in pregnancy pharmacovigilance in the UK.  This blog post will introduce the concept of pharmacovigilance and tell you how you can play a role in this important process.

What is pregnancy pharmacovigilance?

When a new medicine is first launched, the evidence of its safety and effectiveness comes from clinical trials. These trials will have lasted for a certain amount of time, and generally include up to a few thousand people. It is important that the safety of new medicines continues to be monitored after their launch as some very rare side effects may become apparent only with use in much larger numbers of people. The process of monitoring is called pharmacovigilance.

In general, pregnant women are not intentionally included in clinical trials.  Most new medicines will not yet be recommended for use in pregnancy, simply because there is too little information to prove that they are safe. It is inevitable, however, that some pregnant women end up using newly launched medicines (often before they realise they are pregnant). Pharmacovigilance systems ensure that any adverse effects during pregnancy are detected rapidly.

How do we detect effects on the unborn baby?

In order to understand if a medicine can be safely used by pregnant women, we must assess how common certain pregnancy outcomes are following use of the medicine.  These outcomes include; preterm birth (prematurity), miscarriage, stillbirth, the baby being born smaller than expected for the stage of pregnancy, and the presence of birth defects.   In the background population, up to 1 in every 5 pregnancies ends in a miscarriage, and 1 in every 40 babies is born with a birth defect. The job of pregnancy pharmacovigilance is to detect whether a medicine exposure leads to any increase in the chance of these outcomes above the chance in the background population.

For birth defects, we can also look for other clues that suggest a medicine exposure may be the underlying cause. One of these clues is if there is a number of reports of the same type of birth defect following exposure to the medicine.  Another is knowledge of the drug’s mechanism of action, which may tell us whether it is likely to cause a particular defect. Another important clue is if the reported birth defects all follow medicine exposure in early pregnancy (structural birth defects occur mainly in the first trimester). These clues, along with general information about health, lifestyle and use of other medicines in affected pregnancies can help us to determine if there really is a link with taking a particular medicine.

How is the information on new medicines collected?

When a drug company launches a new medicine, they are required by law to continue monitoring its effects. To do this, they invite healthcare professionals and the general public to report any adverse events that have occurred around the time of use. This includes problems in the baby if the medicine was used in pregnancy. The drug company will also use other types of information such as case reports published in scientific journals in the ongoing monitoring of medicine safety. Importantly, this information cannot be used to estimate exactly how many people might experience side effects. This is because this type of reporting generally provides no information about how many people have taken the medicine without any problem.

Information about exposure in pregnancy to new medicines is also collected by teratology information services like UKTIS. We mainly collect information from healthcare professionals who telephone us for advice about their patients and from women who create an online BUMPS Record.  Medicine exposures are most often reported to UKTIS before the pregnancy has ended. This means that UKTIS eventually receives information about both healthy and, occasionally, adverse pregnancy outcomes following medicine exposures. This type of data is very important as it can be used to estimate the chance of a certain pregnancy outcome following a medicine exposure.

What happens if a medicine used in pregnancy is suspected to be linked to an adverse pregnancy outcome?

If a medicine is linked to an adverse pregnancy outcome, its safety information will be updated to reflect the new evidence. The product information leaflets will be revised, and national drug regulatory agencies (such as the MHRA in the UK) might issue specific guidelines to ensure that doctors who prescribe the medicine are aware of the new findings. This allows pregnant women to make a more informed choice about the possible risks of any medicines to an unborn baby, versus the benefits to their health of using the medicine.

The infographic below summarises how collection of pharmacovigilance data can lead to changes that help minimise risk of harm to the mother and baby.

How can I contribute?

In order that the information UKTIS provides is as accurate as possible, we need to collect as many reports as we can on medicine use in pregnancy.
You can help us with data collection by reporting your medicine use in pregnancy here or by asking pregnant women to report to BUMPS if you are a healthcare professional.

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