Research
The National Birth Defects Prevention Study (NBDPS) is a population-based, case-control study that collected data from 1997 until 2013 on babies born between 1997 and 2011. Although the collection of data stopped in 2013, the researchers continue to analyze this rich source of information on birth defects.
The NBDPS is a population-based study because it looks at all birth defects that happened in a certain area. That area was either a state or a number of counties. One of the important things to watch is whether the number of birth defects in the study area changed over time.
The NBDPS is called a case-control study because information was collected from both mothers who had a pregnancy affected by a birth defect (these are called case mothers) and mothers of babies who had not had a birth defect (these are called control mothers; controls). The controls could also be called the comparison group. Controls were chosen by random selection. This means they were chosen by chance from the population in the study area. In the NBDPS, controls were chosen by a computer program that picked babies from birth certificates or birth hospitals in a given month in the study area.
After the interview was completed and the cheek cells had been sent in, the work of the participants was done, but that is when the work of the researchers began.
How is research done?
One of the first steps was coding. During coding, we assigned values to open-ended questions or responses from the interviews that did not fit the multiple-choice options. For instance, different nursing jobs were combined into one nursing group.
All of the information collected was then saved in an anonymous database for use by investigators. Investigators then compare the case group and the control group to see if something happened more or less often in one of the groups. Investigators use a kind of math called statistics to compare the groups. Then, the investigators write papers about what they found. Those papers are reviewed by scientists outside the NBDPS, and the papers are then published in medical journals. To read more about notable NBDPS findings, click here.