Mass General Home

TOPICS ON THIS PAGE: History | Methods | Publications

Sign up for our Email Newsletter

The AED Pregnancy Registry
- The Massachusetts General Hospital

121 Innerbelt Road ~ Room 220 ~ Somerville, MA ~ 02143 ~ Toll Free: 888-233-2334
Sponsored by: AbbVie, Eisai, Novartis, Ortho-McNeil, Pfizer, Sunovion, UCB



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. It was established with funds provided by six companies that manufacture "old" and "new" anticonvulsant drugs. The 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. The highest priority was new information on the many "new" AEDs marketed in the past 10 years.

The AED Pregnancy Registry is the first hospital-based registry established to determine the safety of seizure medications that can be taken by women 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 and goes to great lengths to insure that its research follows scientifically rigorous guidelines in regards to release criteria, anonymity and confidentiality. (For more details, please see the Methods section)

We hope that this method of evaluating drugs will determine which anticonvulsant drugs appear to be safer to use in pregnancy. To do this we need the cooperation of many more eligible women and their health care providers. We are very grateful to the 9,950 women who have enrolled as of September 2015.

return to top


The eligible woman calls the toll-free number (1-888-233-2334) to obtain information and, we hope, to enroll. She is read an informed-consent document over the phone, and can verbally give her consent. She is interviewed 3 times: at enrollment (20 minutes), 7 months' gestation (5 minutes), and 8 weeks after delivery (10 minutes). The findings by the doctor of each exposed infant are obtained with the mother's written permission. The study dysmorphologist uses established inclusion/exclusion criteria to identify major malformations (defined as structural abnormality with surgical, medical, or cosmetic importance). The Scientific Advisory Committee meets separate from the representatives of the sponsoring companies to
anonymously review the major findings. Findings in women who have enrolled before having any prenatal screening, a "pure" prospective group, are used to decide when findings should be released.

The criterion for release of results for a positive association (relative risk, >1) is met when the lower of the 95% confidence interval (CI) is greater than or equal to 2.0. The release criterion for no associated increase in the frequency of all major malformations is met when the upper of the 95% confidence limits does not exceed 2.0. The external comparison group is the findings in the Active Malformations Surveillance Program at Brigham and Women's Hospital. The findings in 69,277 newborns was a baseline rate of 2.24%, which was reduced to 1.62% after excluding infants with genetic disorders and chromosome abnormalities. The major malformations are identified between birth and age 5 days. The inclusion/exclusion criteria are the same as those used in the AED Pregnancy Registry.

return to top


The North American AED Pregnancy Registry has published several articles based on its findings. To view these publications, click here.

return to top