To help rule out the possible contribution of recall bias, researchers also conducted a sensitivity analysis comparing mothers of malformed infants with mothers of infants with other malformations not implicated in the Broussard NBDPS
This study further examines findings from the NBDPS
and follows up on leads to understand more about what causes 17 major birth defects and how to prevent them.
A water module was added to the NBDPS interview in 1999, and questions about personal water use were asked of all mothers beginning in 2000, including sources (private well, unfiltered tap, filtered tap, bottled, other); presence and type of filtration; quantity of water drank at home and at work or school on an average day; and any changes including month/year of change in source or quantity of drinking water consumed.
After maternal residential addresses were geocoded, we used an approach developed by the Water Subcommittee of the NBDPS Environmental/Occupational Work Group to link geocoded addresses to municipal water supplies.
To help rule out the possible contribution of recall bias, a sensitivity analysis was also conducted comparing mothers of malformed infants with mothers of infants with other malformations not implicated in the Broussard NBDPS
Recurrence-control mothers were those who had a previous NTD-affected pregnancy, whose index pregnancy was included in NBDPS as a control.
NBDPS does not collect information on folic acid dosage, and therefore the only indicator of whether a mother might have taken high-dosage folic acid supplement was reported use of a single-ingredient folic acid supplement, in which case it is possible that she took the recommended amount.
The NBDPS CATI includes occupation-related questions for jobs held for at least 1 month from 3 months before conception through the end of pregnancy.
Specifically, as part of the NBDPS occupational exposure assessment, industrial hygienists involved in the project participated in a training session before reviewing the job histories.
They then assessed how each of these indexes performed in predicting risk for isolated (nonsyndromic) neural tube defects and orofacial clefts using data on 9,558 pregnancies in the NBDPS
Future studies of medications and birth defects, possibly using NBDPS
, are needed to address some of the current knowledge gaps on the effects of medication use during pregnancy.
In 1999, we conducted a field study to develop and evaluate, for use in the NBDPS
, exposure measures for DBPs with a special emphasis on individual trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane, and bromoform).