Treatment of hyperthyroidism in pregnancy

One hundred and five consecutive pregnancies in 79 women affected by hyperthyroidism were observed during an 8-year period. All had received treatment either with carbimazole alone (Group I) or with the combination of carbimazole and propranolol (Group II). There were 72 pregnancies in Group I, 33 in Group II. Seventy-five pregnancies occurred whilst the mother was receiving antithyroid therapy and in the other 30 the diagnosis of hyperthyroidism was made following conception. The total fetal loss was 17.1%, with a spontaneous abortion rate of 5.5% in Group I and 24.2% in Group II. No congenital malformation or maternal deaths occurred. Carbimazole is safe and effective during pregnancy. Adding propranolol offers no further advantage and may indeed be detrimental.