title: Does the average drug exposure in pregnant women affect pregnancy outcome? A comparison of two approaches to estimate the baseline risks of adverse pregnancy outcome.
abstract: OBJECTIVE
  The results of observational cohort studies on drug effects on pregnancy outcome may depend among others on suitable comparison cohorts. The aim of this investigation was to compare two distinct definitions of maternal exposure status for comparison cohorts.
  
  
  METHODS
  We performed an observational cohort study of prospectively ascertained pregnant women who spontaneously contacted the Teratology Information Service (TIS) Berlin for drug risk consultation. The only exclusion criteria were exposures to established teratogens and/or fetotoxicants. Pregnancy outcomes of 3250 women with this "average drug exposure" were compared with 546 non-exposed or insignificantly exposed pregnancies.
  
  
  RESULTS
  Neither the rate of major birth defects (3.0%; aOR 1.62; 95% CI 0.8-3.3) nor the risk of spontaneous abortion (16.0%; aHR 1.20; 95% CI 0.8-1.7) was significantly increased after average drug exposure, whereas the rate of electively terminated pregnancies was higher (11.1%; aHR 2.05; 95% CI 1.2-3.4). There were no differences in the risk of preterm birth (9.9%; aOR 1.38; 95% CI 0.9-2.0) and infants' birth weight (p = 0.60).
  
  
  CONCLUSIONS
  This study does not provide evidence for an increased risk of adverse pregnancy outcome after average drug exposure during pregnancy. Therefore, comparison cohorts with average drug exposure are appropriate for studies on potential teratogens or fetotoxicants based on observational data collected by TIS.
authors: Pharmakovigilanz- und Beratungszentrum für Embryonaltoxikologie (Institute for Clinical Teratology and Drug Risk Assessment in Pregnancy), Charité Universitätsmedizin Berlin, Berlin, Germany.
authors: Evelin
authors: E
authors: Wacker
authors: Ana
authors: A
authors: Navarro
authors: Reinhard
authors: R
authors: Meister
authors: Stephanie
authors: S
authors: Padberg
authors: Corinna
authors: C
authors: Weber-Schoendorfer
authors: Christof
authors: C
authors: Schaefer
mesh_terms: D000014:Abnormalities, Drug-Induced / Q000453:epidemiology*; D000028:Abortion, Induced / Q000706:statistics & numerical data; D000022:Abortion, Spontaneous / Q000453:epidemiology; D000328:Adult; D001724:Birth Weight; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D064887:Observational Studies as Topic; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D047928:Premature Birth / Q000453:epidemiology; D011446:Prospective Studies; D012307:Risk Factors; D013997:Time Factors
keywords: comparison cohort; drug safety; observational cohort study; pharmacoepidemiology; pregnancy; prospective