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Background: The National Birth Defects Prevention Study (NBDPS) is a large population-based multicenter case-control study of major birth defects in the United States., Methods: Data collection took place from 1998 through 2013 on pregnancies ending between October 1997 and December 2011. Cases could be live born, stillborn, or induced terminations, and were identified from birth defects surveillance programs in Arkansas, California, Georgia, Iowa, Massachusetts, New Jersey, New York, North Carolina, Texas, and Utah. Controls were live born infants without major birth defects identified from the same geographical regions and time periods as cases by means of either vital records or birth hospitals. Computer-assisted telephone interviews were completed with women between 6 weeks and 24 months after the estimated date of delivery. After completion of interviews, families received buccal cell collection kits for the mother, father, and infant (if living)., Results: There were 47,832 eligible cases and 18,272 eligible controls. Among these, 32,187 (67%) and 11,814 (65%), respectively, provided interview information about their pregnancies. Buccal cell collection kits with a cytobrush for at least one family member were returned by 19,065 case and 6,211 control families (65% and 59% of those who were sent a kit). More than 500 projects have been proposed by the collaborators and over 200 manuscripts published using data from the NBDPS through December 2014., Conclusion: The NBDPS has made substantial contributions to the field of birth defects epidemiology through its rigorous design, including case classification, detailed questionnaire and specimen collection, large study population, and collaborative activities across Centers., (© 2015 Wiley Periodicals, Inc.)

Background: Nonresponse bias assessment is an important and underutilized tool in survey research to assess potential bias due to incomplete participation. This study illustrates a nonresponse bias sensitivity assessment using a survey on perceived barriers to care for children with orofacial clefts in North Carolina., Methods: Children born in North Carolina between 2001 and 2004 with an orofacial cleft were eligible for inclusion. Vital statistics data, including maternal and child characteristics, were available on all eligible subjects. Missing 'responses' from nonparticipants were imputed using assumptions based on the distribution of responses, survey method (mail or phone), and participant maternal demographics., Results: Overall, 245 of 475 subjects (51.6%) responded to either a mail or phone survey. Cost as a barrier to care was reported by 25.0% of participants. When stratified by survey type, 28.3% of mail respondents and 17.2% of phone respondents reported cost as a barrier. Under various assumptions, the bias-adjusted estimated prevalence of cost as barrier to care ranged from 16.1% to 30.0%. Maternal age, education, race, and marital status at time of birth were not associated with subjects reporting cost as a barrier., Conclusion: As survey response rates continue to decline, the importance of assessing the potential impact of nonresponse bias has become more critical. Birth defects research is particularly conducive to nonresponse bias analysis, especially when birth defect registries and birth certificate records are used. Future birth defect studies which use population-based surveillance data and have incomplete participation could benefit from this type of nonresponse bias assessment. Birth Defects Research (Part A) 103:603-609, 2015. © 2015 Wiley Periodicals, Inc., (© 2015 Wiley Periodicals, Inc.)

Background: Limb reduction deficiencies that are accompanied by amniotic bands (AB-Ls) and terminal transverse limb deficiencies (TLDs) have each been attributed to vascular disruption; for the former, however, it is not clear if amniotic bands are the primary cause of or are secondary to vascular disruption. If amniotic bands are secondary to vascular disruption, then a shared pathogenesis for each case group might be exhibited by similar risk factors., Methods: We evaluated maternal age, education, race/ethnicity, parity, pregnancy wantedness, and vasoactive exposures among 139 AB-L and 373 TLD cases, using interview data collected from mothers in 10 states by the National Birth Defects Prevention Study. Vasoactive exposures included maternal cigarette smoking and use of decongestants, nonsteroid anti-inflammatory drugs, and antihypertensive drugs in the periconceptional period., Results: Increased risk estimates were observed for Black mothers (OR 2.5; 95% CI: 1.5-4.1) and nulliparous mothers (2.1; 1.4-3.0) in relation to AB-L, while neither was associated with TLD. Hispanic women (1.4; 1.0-1.9) and those not wanting the pregnancy (1.5; 1.1-2.1) had increased risks of TLD, but not AB-L. Maternal cigarette smoking and aspirin use each increased the risk of AB-L, but not TLD; while decongestants and possibly antihypertensive medications increased the risk of TLD, but not AB-L., Conclusions: The lack of consistent findings for the two case groups suggests that AB-L and TLD may be distinct entities. The inconsistencies also suggest that these vasoactive exposures may not be markers for vascular disruption or that vascular disruption may not play a major role in the pathogenesis of these two types of limb deficiencies.