Accuracy of prenatal smoking data from Washington State birth certificates in a population-based sample with cotinine measurements.
OBJECTIVE
To assess the accuracy of smoking data in contemporary U.S. birth certificates.


METHODS
We compared data on prenatal smoking as reported on Washington State birth certificates to cotinine measured in archived newborn screening dried blood spots for 200 infants born in 2007 (100 randomly selected from births to self-reported nonsmokers and 100 born to self-reported smokers). We estimated the sensitivity of the birth certificate data to identify prenatal smokers and the precision with which self-identified third trimester smokers report smoking levels.


RESULTS
Infants born to two (2%) mothers who reported they did not smoke during the pregnancy had whole blood cotinine concentrations consistent with active smoking by the mother (sensitivity 85%). Sensitivity of the birth certificate to identify reported smokers who continued to smoke throughout pregnancy was similar (89%). Among self-identified third trimester smokers whose infants' specimens were collected shortly after delivery, Spearman rho between infant cotinine and maternal-reported cigarettes/day in the third trimester was 0.54.


CONCLUSIONS
Birth certificates may represent a viable option for assessing prenatal smoking status, and possibly smoking cessation and level among smokers, in epidemiologic studies sufficiently powered to overcome a moderate amount of exposure measurement error.
Fred Hutchinson Cancer Research Center, Public Health Sciences Division, Seattle, WA. Electronic address: snielsen@fhcrc.org.
Susan
S
Searles Nielsen
Environmental Health Laboratory and Trace Organics Analysis Center, Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA.
Russell L
RL
Dills
Washington State Department of Health, Newborn Screening Program, Shoreline, WA.
Michael
M
Glass
Fred Hutchinson Cancer Research Center, Public Health Sciences Division, Seattle, WA.
Beth A
BA
Mueller
D015982:Bias; D001719:Birth Certificates; D003367:Cotinine / Q000097:blood*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008425:Maternal Behavior; D009035:Mothers / Q000523:psychology*; D011159:Population Surveillance; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D012680:Sensitivity and Specificity; D012907:Smoking / Q000097:blood* / Q000453:epidemiology / Q000523:psychology; D016540:Smoking Cessation / Q000706:statistics & numerical data*; D014861:Washington / Q000453:epidemiology
D003367:Cotinine
Bias (Epidemiology); Birth certificates; Cotinine; Pregnancy; Sensitivity and specificity; Smoking; Smoking cessation