Medical databases in studies of drug teratogenicity: methodological issues

Figures & data

Table 1 Examples of North American and European medical databases suited for studies of teratogenicity of drugs

Example of a database or a linked set of databases	Country	Population covered	Measure of prenatal drug exposure	Measure of birth defects’ occurrence
Medicaid^Citation16	USA	Pregnant women and children eligible as determined by state-specific low-income definitions	Medicaid maternal pharmacy files	Medicaid-maintained records of hospitalizations, emergency-department and outpatient physician visits
Private insurance claims databases^Citation18	USA	Enrollees of participating health care plans, such as HMOs	Health-plan maintained records of dispensed prescriptions	Health-plan maintained hospitalization, outpatient, and emergency-department records
Saskatchewan Health Services Databases^Citation19	Canada	Population of the Saskatchewan province (99%)	Outpatient prescription drugs database	Hospitalization database Medical services database Vital statistics database
The General Practice Research Database^Citation13^–^Citation15	UK	A sample of UK patients	Electronic medical records	Electronic medical records
Population medical Databases of Nordic countries^Citation9,Citation21^–^Citation25	Denmark, Finland, Iceland, Norway, Sweden	Entire country populations	Nationwide and regional prescription databases; maternal self-report recorded in the birth registry	Birth registries, registers of congenital malformations, hospital discharge registries, registries of induced abortions
Teratology information services^Citation30,Citation31	Worldwide	May or may not cover a well-defined population	Self-report by women	Self-report by women during a TIS-conducted interview

Table 2 Outcomes of gestation and detection of birth defects

Gestational period	Trimester I (up to week 12)	Trimester II (13–28 weeks)	Trimester III (>28 weeks)
Reproductive outcomes	Early spontaneous pregnancy loss due to chromosomal abnormalities (eg, most trisomies)	Induced pregnancy termination after prenatal diagnosis	Live birth Still birth
	Early miscarriage, malformation rarely observed	Late spontaneous miscarriage
	Nontherapeutic elective abortion
Detection of malformations	Spontaneous abortions of chromosomal abnormalities and elective abortions are unlikely to be related to malformation or drug use Other birth defects are not observable	Birth defects are observable to some extent	Birth defects are observable

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