How were study participants selected?

Part of our on-going work to find causes of birth defects includes studying them when they occur. Women whose babies did not have birth defects were selected randomly from women who gave birth in the same area during the same year. These families were contacted to find out if they wanted to participate in the study.

Participation of mothers of babies without birth defects

Answers and cheek cell samples provided by mothers of babies with no birth defects (control mothers) were compared to answers and cheek cell samples provided by mothers of babies affected by birth defects (case mothers). If case mothers reported exposure to something more often than control mothers, this could mean that the exposure is related to the birth defect. An exposure can be something a person eats, a drug or medical treatment, or something used on the job. DNA from cheek cell samples allows us to look at the role of genetic factors in birth defects, especially those that interact with other exposures.

How do I withdraw from the study?

NBDPS began interviewing mothers more than 20 years ago! Some babies of the earliest participants have reached the age of 18. Participants can withdraw themselves and/or their child from the study at any time. In addition, when a child reaches the age of 18, he or she can also decide to withdraw from the study at any time. Withdrawing for a child means we will destroy the cheek-cell sample that we received when he/she was a baby. That means the sample will not be used. To withdraw from the study, call 1-888-743-7324 or e-mail For any person who withdraws from the study, we will not use their data in the future, but we cannot remove their data from findings or articles that have already been published. Please note that no publications include specific information that can identify a particular person.