How did the NBDPS collect information?
The NBDPS collected two different types of data: interview and genetic data.
Interview
The team used interviews to collect information from women. A computer guided the interviewers in asking the questions, so every woman was asked the same questions in the same way. Sometimes after an interview, the interviewer would call a woman back to clarify her answers or get more information. The interview covered a wide range of topics. Researchers were interested in the pregnancy period and three months before pregnancy. Questions were asked about:
- Past pregnancies
- Health and diet
- Prescription and non-prescription drugs
- Work and hobbies
- Lifestyle
- Father's work and lifestyle
Cheek cells
The NBDPS team sent out small brushes to each family to collect cheek cells from biological mothers, fathers, and babies, when possible. These brushes were sent back to the NBDPS laboratory where they are stored securely without the family's name.
Genetic data
The cheek cells contain genes. Genes are part of long strands of cell material called DNA. Strands of DNA are found inside each of the cells of the body. Each gene on the DNA strand has special instructions that tell the cell what to do. For example, one gene might tell the cell how to make the chemicals that help us digest food. Investigators look at the cheek cells in the lab to see if there are differences in specific genes between the cases and controls.