The North American AED (Antiepileptic Drug) Pregnancy Registry



The North American AED (Antiepileptic Drug) Pregnancy Registry was established in 1997 for pregnant women in the United States and Canada at the Massachusetts General Hospital in Boston, Massachusetts as a philanthropic arm of Harvard Medical School. It was established with funds provided by six companies that manufacture “old” and “new” anticonvulsant drugs. Our major objective is to obtain and publish information on the frequency of major malformations, such as heart defects, spina bifida and cleft lip, among infants whose mothers had taken one or more AEDs to prevent seizures or to treat any other medical condition during pregnancy. The highest priority was new information on the many “new” AEDs marketed in the past 10 years.

The North American AED (Antiepileptic Drug) Pregnancy Registry is the first hospital-based registry established to determine the safety of seizure medications during pregnancy. Before the creation of this pregnancy registry, there was no systematic method for determining whether or not each commonly used anticonvulsant drug was associated with an increased frequency of malformations in comparison to infants not exposed to these drugs. In the past, this type of research has only been done by the manufacturers of these drugs. The Registry is proud to be conducting this research within a non-biased academic setting. We go to great lengths to ensure that our research follows scientifically rigorous guidelines in regard to release criteria, anonymity, and confidentiality.

We hope that this method of evaluation will determine which anticonvulsant drugs appear safer to use during pregnancy. To do this we need the cooperation of many more eligible women and their health care providers. We are very grateful to the over 13,500 women who have enrolled as of February, 2021.


When was the North American AED (Antiepileptic Drug) Registry started?
The North American AED (Antiepileptic Drug) Pregnancy Registry was established in 1997. It is a philanthropic arm of Harvard Medical School and housed at Massachusetts General Hospital.

How many women have enrolled?
As of February, 2021 more than 13,500 women had enrolled in the North American AED (Antiepileptic Drug) Registry.

Where are these women from?

The participants of the North American AED (Antiepileptic Drug) Registry represent all 50 U.S. states and all 10 Canadian provinces.

What drugs are included in the study?

For a list of drugs that are included in the North American AED (Antiepileptic Drug) Registry, please see our Medications Page.

How many women with epilepsy are taking these medications?

In the United States alone there are an estimated 1.1 million women with epilepsy of child bearing age.

What impact does my involvement have on other women taking AEDs?

By enrolling in the North American Antiepileptic Drug Pregnancy Registry you add to a growing body of research that helps determine which medications appear safest during pregnancy.

In addition to the estimated 1.1 million women who have epilepsy and are of child bearing age, there are countless pregnant women who need to take AEDs for pain management, mood disorders, and other conditions. The Registry aims to inform and support these women by gathering and publishing research in top journals. Your pregnancy story and outcome gives other pregnant women a framework from which to consider their pregnancy journey and make more well-informed decisions around AED usage.

Further, as we study the safety of AEDs during pregnancy, the frequency and accuracy of our findings remain contingent upon the largest possible sample size. Every woman who enrolls adds to the strength of our study.

How is my participation in your Registry helping others?

By participating in the Registry, you help pregnant women, their infants, and their healthcare providers.

The Registry serves as a storehouse of information about AEDs. That storehouse would not exist without the participation of thousands of pregnant women. When pregnant women visit the registry, and become part of our work, they are taking a step to inform themselves and their pregnant peers about their health and the health of their infants. The information you supply as a Registry participant may be used in helping to counsel pregnant women in the future.

On the healthcare provider side, many providers refer pregnant women to the Registry and the providers in turn benefit from our growing body of research. When it comes time to deciding which AEDs to prescribe to pregnant women, providers can consult our research for findings on the risks associated with several medications.

What do you do with the information collected from me?

The information we obtain about you and your infant is kept in an electronic database that is password protected. The information we collect is shared with study investigators, but is stripped of your name and personal health identifiers.

All medical records obtained by the Registry are obtained via the written, informed consent of enrollees. The information about you and your baby expires after six months, is HIPAA-compliant, anonymous, and encrypted. In other words, your information becomes part of an ever-growing pool of data and adds to the big picture of AED usage and pregnancy, but your information as an individual is private and protected by HIPAA standards. Based on your input, the Registry publishes annually on our website a list of AEDs and their risk trends over time .

If I am not taking an AED but am pregnant, why is my participation important?

We enroll women who are not taking AEDs while they are pregnant and use this “control” group as a comparison to women who are taking AEDs. Control groups allow researchers to determine whether a treatment under investigation has a significant effect .

In other words, enrolling pregnant women who are not taking AEDs helps us better determine how pregnant women who are taking AEDs might be impacted by the drugs. If we limited our research to the study of pregnant women who take AEDs, we would have no basis for comparison and the data may become less meaningful over time. Pregnant women who are not taking AEDs are critical contributors to our work.

If my medication is not on your list of studied medications, can I still participate?

The short answer is a resounding yes. If you are currently pregnant and taking any AED for any reason, we want to hear from you. Our list of medications is not static, so capturing data about an AED that we do not currently follow is beneficial to the study and to the future of AED usage by pregnant women.

Dr. Lewis Holmes included in his vision for the Registry a goal of having a system in place to study a new drug’s effect on pregnancy outcomes as soon as it hits the market; information about any AED a pregnant woman might be taking helps us steer in the direction of that goal.

Why should I stick with the Registry and answer any questions/calls from your team even after my baby is born?

We value our relationships with our enrollees and want to hear about your developing experience from conception through the post-natal period and beyond. The outcome of your pregnancy and your infant’s ongoing health is of utmost importance to us. A clear picture of your infant’s health contributes to our understanding of how AED usage in pregnant women may or may not manifest certain outcomes in their infants. To put it another way, we are equally interested in the mother’s health and that of the infant.

Another reason to remain in contact with the Registry after your baby is born is that the impact of AEDs may sometimes be seen on prenatal ultrasounds, but until the baby is born the true impact cannot be fully determined. We exclude prenatal ultrasound findings unless they are identified at birth by the examining pediatrician, because ultrasound findings are not as reliable as a postnatal exam. Also, in some cases, tests and exams happen in the later months of the baby’s first year of life. The results of such tests may be important in determining the impact of AEDs on pregnant women and their infants. Simply put, we strive to maintain contact with mothers after their baby is born in order to log the most complete set of data.