hospitals delivering less than 1250 babies per year and a quarter were born in one of the 80 hospitals delivering less than 675 babies per year.6 However, when performed after 24 hours and with repeat screening performed after an initial screening failure, the positive predictive value of pulse oximetry for potentially life-threatening heart disease is between 21% and 26%.4, 30 This data suggests that in settings where echocardiography is not available, it may be reasonable to extend the hospitalization of an asymptomatic newborn to allow for additional evaluation and to allow transitional circulation to resolve or to transfer the baby to a facility where echocardiography can be performed. Conclusion When performed after 24 hours and repeated if abnormal, the use of pulse oximetry is a viable method of screening asymptomatic neonates for critical congenital heart disease. Based on the morbidity and mortality related to the missed diagnosis of congenital heart disease in the newborn and the growing body of evidence demonstrating the benefits pulse oximetry screening, the use of pulse oximetry is likely to become more widespread in the near future. Acknowledgements I would like to thank Tracey S. Hokanson RN, PNP; Douglas Schneider, MD; and Ms. Amy Basken for their review of this manuscript. Causes of Birth Defects: An Epidemiological Mystery by Trish Strohfeldt West Bend East High School, West Bend, Wisconsin In collaboration with the Centers for Disease Control and Prevention’s Jennita Reefhuis In this lesson students will be presented with a problem – a cluster of unexplained neural tube birth defects are occurring in a town. Students will take on different roles (physician, parent, epidemiologist, lab technician, etc.) to investigate possible causes of the increased occurrence of birth defects, and then use the evidence gathered to propose the most probable cause. The focus of the lesson is to better understand the process of investigating a scientific problem and the many risk factors associated with birth defects. Disclaimer: The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the Centers for Disease Control and Prevention. Learning Outcomes Causes of Birth Defects: An Epidemiological Mystery by Trish Strohfeldt West Bend East High School West Bend, Wisconsin Summary In this lesson students will be presented with a problem a cluster of unexplained neural tube birth defects are occurring in a town. Students will take on different roles (physician, parent, epidemiologist, lab technician, etc.) to investigate possible causes of the increased occurrence of birth defects and then use the evidence gathered to propose the most probable cause. The focus of the lesson is to better understand the process of investigating a scientific problem and the many risk factors associated with birth defects. • The student will become more familiar with how the scientific process works (several groups working together, research, revising a hypothesis, sharing information) when investigating the cause of a cluster of a disorder “Become more familiar” seems like a broad objective. • The student will be able to describe risk factors associated with birth defects • The student will be able to describe the many roles of the people (physician, epidemiologist, lab technician, etc.) involved with studying the probable cause of a cluster. Materials 1. Computers with access to Internet for each student. 2. Copies of handouts for each student (“Pretest” and “’Investigation Sheet” from the Introduction, and “Rubric for the Final Report” from the Conclusion) Total Duration 2 hours Procedures Teacher Preparation The teacher should make photocopies of the required handouts (“Pretest” and “’Investigation Sheet” from the Introduction, and “Rubric for the Final Report” from the Conclusion) for each student. The teacher needs to put together enough copies of each of the case file folders so that each student assigned each role has a folder for his/her role that contains the necessary files. If Internet access is not available for every student, the teacher should go to the Web resources listed for each role in Step 2 and print out the pages to put in the files In Step 2, the teacher should give each student different resources (copies of the Web sites listed for each role and any files for each role) to encourage them to work together, share information, and solve the problem. It is suggested to make the copies for each file a different color for easy sorting (for example, all parent files blue, all physician files red, etc.). Several references are listed below that a teacher might want to explore before beginning the lesson. 5Fborder.shtm 4. Birth defects in the lower Rio Grande Valley-A special report of the Texas birth defects monitoring division. December 15, 1998. Available from URL:.pdf Begin the lesson by giving the “Pretest” to the students. Have them try to complete the questions and then discuss their responses. Answers are provided in the “Pre-Test Answer Key” for the teacher’s reference; however do not review the answers with the students yet, as they will be researching these topics as they work through the lesson. Read the introduction “Request for Investigation” about the reports of birth defects. Encourage students to write down on their “Investigation Sheet” any facts that they think might