Table 3: Types of major congenital malformations observed.

Type of major malformationNumber of malformationsOdds ratio
ExposedUnexposed(95% CI)

Congenital malformations of the nervous system2 (0.5%)686 (0.1%)3.79 (0.94–15.25)
Neural tube defects1 (0.3%)234 (0.0%)5.55 (0.78–39.68)
Congenital malformations of the eye0 (0%)586 (0.1%)
Congenital malformations of the ear, face, and neck0 (0%)274 (0.1%)
Congenital malformations of the heart7 (1.7%)3682 (0.7%)2.49 (1.18–5.26)
Congenital malformations of the respiratory system0 (0%)469 (0.1%)
Orofacial clefts2 (0.5%)1036 (0.2%)2.51 (0.62–10.09)
Congenital malformations of the digestive system2 (0.5%)993 (0.2%)2.62 (0.65–10.52)
Abdominal wall defects0 (0%)145 (0.0%)
Congenital malformations of the external genital organs1 (0.3%)1442 (0.3%)0.82 (0.13–6.40)
Congenital malformations of the internal urinary system1 (0.3%)1273 (0.2%)1.02 (0.14–7.25)
Congenital malformations of the limbs9 (2.2%)5416 (1.0%)2.18 (1.13–4.23)
Congenital malformations of the musculoskeletal system 1 (0.3%)798 (0.2%)1.62 (0.22–11.60)
Other malformations1 (0.3%)662 (0.1%)1.96 (0.28–13.98)
Teratogenic syndromes with malformations0 (0%)38 (0.0%)
Genetic syndromes and microdeletions1 (0.3%)315 (0.1%)4.62 (0.58–29.44)
Chromosomal abnormalities1 (0.3%)653 (0.1%)1.99 (0.28–14.17)

All major congenital malformations25 (6.2%)17,465 (3.4%)1.91 (1.28–2.87)
All minor congenital malformations18 (4.5%)11,600 (2.2%)2.06 (1.28–3.31)
All congenital malformations40 (10.0%)27,173 (5.2%)2.01 (1.45–2.78)

Major congenital malformations among children of mothers exposed to trimethoprim in the 12-week period prior to conception and among unexposed according to the EUROCAT classification system.