EGA Institute for Women's Health


Maternal and Fetal Adverse Event Terminology: MFAET

A new system to provide better safety monitoring for clinical trials in pregnancy.

pregnant woman taking a tablet

Conducting clinical trials in pregnancy raises many challenges, primarily due to safety concerns for the mother and her fetus (unborn baby). This is particularly the case when testing new maternal and fetal therapies. To assess therapeutic safety, we can monitor important signals about the wellbeing of the mother and fetus, called Adverse Events or AEs.

What are Adverse Events?

Adverse Events or AEs are defined as “any untoward medical occurrence in a patient or clinical trial participant administered a medicinal product and which does not necessarily have a causal relationship with this product.”

To assess the safety of a drug or intervention, researchers record any AEs which occur during clinical trials. AEs have standard definitions to ensure good communication between clinical trial staff. And to get the most detailed safety data, these AEs are usually graded from 1 to 5. Standard criteria exist for defining and grading hundreds of AEs outside pregnancy.  The Common Terminology Criteria for Adverse Events (CTCAE) is the most commonly used grading system listing hundreds of AEs.

But historically there has been a lack of a comprehensive Adverse Event framework in pregnancy trials, with only a handful of AEs available. This has severely limited the understanding of risks in conducting clinical trials in pregnant women.

The new MFAET terminology aims to transform the conduct of clinical trials in pregnancy, making them much safer for pregnant women and their babies.

MFAET: Maternal Fetal Adverse Event Terminology

MFAET is a comprehensive system of definitions and grading of maternal and fetal AEs. This work was lead by the EVERREST International Adverse Event Consensus Group of fetal therapy, obstetric, neonatal, and pharmaceutical industry experts from Europe and the United States. An international consensus process has now agreed the terminology.  The current version is 1.1., February 2022, which has now been realigned with the corresponding terms in the  Medical Dictionary for Regulatory Activities (MedDRA).

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