Questions about dexamethasone use for the prevention of anti-SSA related congenital heart block

Mothers with anti-SSA/Ro antibodies who have had a previous fetus with congenital heart block (CHB) have a risk of recurrence estimated to be up to 16%.

To improve the management of these "high risk patients" by determining (a) whether or not prophylactic treatment is efficient; (b) whether or not fluorinated steroids (betametasone and dexamethasone) that do cross the placenta in an active form are safe for the fetus; and (c) which prophylactic treatment should be used.

Retrospective study performed on seven mothers sent to a university hospital owing to a past history of one (six mothers) or two children (one mother) with CHB.

13 subsequent pregnancies occurred. No CHB was observed. All four pregnancies in women treated with 10 mg/day prednisone were uneventful. Three pregnancies in women receiving no steroids resulted in two early spontaneous abortions and one live birth. The six pregnancies in women treated with dexamethasone (4-5 mg/day) ended in one early and one late spontaneous abortion, two stillbirths, and two live births with intrauterine growth restriction and mild adrenal insufficiency. A histological study of one stillbirth disclosed intrauterine growth restriction and marked adrenal hypoplasia.

Adverse obstetric outcomes were often seen here and major concerns have been raised by paediatricians about the safety of fluorinated steroids, owing to the results of animals studies, retrospective data, and randomised trials. Because fluorinated steroids have not been shown to improve prophylactic treatment of CHB in pregnant women at high risk, their use is questionable.