title: Methods of linking mothers and infants using health plan data for studies of pregnancy outcomes.
abstract: OBJECTIVE
  Research on medication safety in pregnancy often utilizes health plan and birth certificate records. This study discusses methods used to link mothers with infants, a crucial step in such research.
  
  
  METHODS
  We describe how eight sites participating in the Medication Exposure in Pregnancy Risk Evaluation Program created linkages between deliveries, infants and birth certificates for the 2001-2007 birth cohorts. We describe linkage rates across sites, and for two sites, we compare the characteristics of populations linked using different methods.
  
  
  RESULTS
  Of 299,260 deliveries, 256,563 (86%; range by site, 74-99%) could be linked to infants using a deterministic algorithm. At two sites, using birth certificate data to augment mother-infant linkage increased the representation of mothers who were Hispanic or non-White, younger, Medicaid recipients, or had low educational level. A total of 236,460 (92%; range by site, 82-100%) deliveries could be linked to a birth certificate.
  
  
  CONCLUSIONS
  Tailored approaches enabled linking most deliveries to infants and to birth certificates, even when data systems differed. The methods used may affect the composition of the population identified. Linkages established with such methods can support sound pharmacoepidemiology studies of maternal drug exposure outside the context of a formal registry.
authors.affiliation: Group Health Research Institute, Group Health Cooperative, Seattle, WA, USA.
authors.forename: Karin E
authors.initials: KE
authors.lastname: Johnson
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Beaton
authors.forename: Susan E
authors.initials: SE
authors.lastname: Andrade
authors.forename: T Craig
authors.initials: TC
authors.lastname: Cheetham
authors.forename: Pamela E
authors.initials: PE
authors.lastname: Scott
authors.forename: Tarek A
authors.initials: TA
authors.lastname: Hammad
authors.forename: Inna
authors.initials: I
authors.lastname: Dashevsky
authors.forename: William O
authors.initials: WO
authors.lastname: Cooper
authors.forename: Robert L
authors.initials: RL
authors.lastname: Davis
authors.forename: Pamala A
authors.initials: PA
authors.lastname: Pawloski
authors.forename: Marsha A
authors.initials: MA
authors.lastname: Raebel
authors.forename: David H
authors.initials: DH
authors.lastname: Smith
authors.forename: Sengwee
authors.initials: S
authors.lastname: Toh
authors.forename: De-Kun
authors.initials: DK
authors.lastname: Li
authors.forename: Katherine
authors.initials: K
authors.lastname: Haffenreffer
authors.forename: Sascha
authors.initials: S
authors.lastname: Dublin
mesh_terms: D000293:Adolescent; D000328:Adult; D016907:Adverse Drug Reaction Reporting Systems; D000465:Algorithms; D001719:Birth Certificates; D016009:Chi-Square Distribution; D057225:Data Mining; D016208:Databases, Factual / Q000706:statistics & numerical data; D011307:Drug Prescriptions; D017723:Drug Utilization Review; D005006:Ethnicity; D005260:Female; D006302:Health Services Research; D006801:Humans; D007231:Infant, Newborn; D008498:Medical Record Linkage; D016347:Medical Records Systems, Computerized / Q000706:statistics & numerical data; D018743:Perinatal Care / Q000191:economics / Q000706:statistics & numerical data; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000191:economics / Q000208:ethnology; D044469:Racial Groups; D012959:Socioeconomic Factors; D014481:United States / Q000453:epidemiology; D055815:Young Adult
keywords: Medicaid; birth certificates; medical record linkage; pharmacoepidemiology; pregnancy outcome/epidemiology