EGA Institute for Women's Health


How is this useful for patients and the public?

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What are adverse events and why do they matter? 

An adverse event or AE is anything negative which happens to any person taking part in a clinical trial where they have received an intervention or treatment which is being studied, such as a drug or a surgery. AEs are also recorded for people who are in control groups and do not receive study interventions. Control groups are used to show whether there is a difference in the number and types of negative things which happen during a clinical trial.

What did we want to do?

We wanted to provide a set of set of categories for assessing AEs and their seriousness for pregnant women taking part in trials and for their unborn babies (fetuses). Categories like this already exist for children and adults who are not pregnant who take part in trials. But there were none which were adapted to pregnant women and babies in the womb.

Our set of categories can now be used by researchers and healthcare professionals carrying out studies of treatments which involve pregnant women. This work is also relevant to people who are pregnant but who do not identify as women.

How did we do it?

We set up a group of healthcare and research experts from countries across the world and different areas of medicine and research. We looked at existing published work in the area and we produced a set of descriptions of different AEs. We also generated ways of deciding how serious each AE was, depending on exactly what had happened. Where possible we adapted these from existing general definitions. We also consulted a group of people who were members of the public, representing charities interested in care for women with complicated pregnancies. We then used a type of formal consultation known as a Delphi consensus to reach agreement among a wider group of experts from different countries and medical areas. This was done in several stages, with agreement needed at each stage before we reached a final agreement on each definition and rating of seriousness.

What did we produce?

We have produced two frameworks for AEs with advice and definitions for deciding how serious these are. One set is maternal – for assessing events affecting the pregnant woman. One set is fetal – for events affecting the unborn baby. These are ready to be used by researchers and health professionals who are carrying out studies in pregnant women.

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Why is this important?

It is very important to record all the AEs that happen to a person taking part in a clinical trial. The events may or may not be related to the treatment the person has been given. But it is important to record them all reliably and consistently in order to have a clear picture of how safe the treatment is. It is also important to know how serious an event is; this can vary from mild to life-threatening or fatal.

Pregnant women are not included in most clinical trials because of concern about their safety and the safety of their unborn babies. Sometimes a clinical trial needs to include pregnant women because it is studying a treatment which they will be given because of complications with the mother’s health. Sometimes the trial is looking at treatments for an unborn baby which can be given in the womb. This might include a surgical procedure or a medicine given to the pregnant woman to benefit the baby.

Having standard frameworks for recording and deciding the seriousness of AEs will help to make trials in pregnant women safer for both them and their unborn babies. It will also help to improve research on treatments for pregnant women or babies in the womb by improving collection and publishing of important information.