Table 1 Characteristics of study participants.

N/A, not available.

StudyLocationDesignN (cases)Male/femaleMean gestational days (SD)
RATSSStockholm, SwedenNational prospective twin cohort75 (20)46:29247 (9)
ALSPACBristol, UKCase-control nested in prospective cohort50 (25)36:14271 (21)
Seaver Autism CenterNew York, USAHospital-based case-control18 (10)12:6258 (21)
Autism Tooth Fairy StudyTexas, USACommunity-based case-control50 (25)25:25N/A