High doses of inhaled corticosteroids during the first trimester of pregnancy and congenital malformations

Background

Although reassuring data exist on the use of low-to-moderate doses of inhaled corticosteroids (ICSs) during pregnancy, there are inadequate data for women receiving high doses.

Objective

To investigate the association between doses of ICS during the first trimester of pregnancy and the risk of congenital malformations among women with asthma.

Methods

We conducted a cohort study of 13,280 pregnancies of women with asthma (1990-2002) by linking 3 administrative databases from Quebec (Canada). By using generalized estimation equation models, we compared women taking >0 to 1000 μg/d ICS (beclomethasone dipropionate–chlorofluorocarbone equivalent) with women taking >1000 μg/d and those not taking ICSs. The main outcome measures were all and major congenital malformations.

Results

We identified 1257 infants with a congenital malformation (9.5%) and 782 infants with a major malformation (5.9%). We found that women who used >1000 μg/d ICS (n = 154) were significantly more likely (63%) to have a baby with a malformation than the 4392 women who used >0 to 1000 μg/d (adjusted risk ratio, 1.63; 95% CI, 1.02-2.60). On the other hand, women who used >0 to 1000 μg/d were not found to be more at risk than women who did not use ICSs during the first trimester (n = 8734). Nonsignificant trends of similar magnitude were found for major malformations.

Conclusions

Our study adds evidence on the safety of low-to-moderate doses of ICS taken during the first trimester but raises concerns about high doses. However, we cannot rule out the possibility of residual confounding by severity in this association.

Key words: Asthma, pregnancy, inhaled corticosteroids, congenital malformations, cohort study

Abbreviations used: ED, Emergency department, ICD-9, International Classification of Diseases, Ninth Revision, ICS, Inhaled corticosteroid, ISQ, Institut de la statistique du Québec, MED-ECHO, Maintenance et Exploitation des données pour l'étude de la clientèle hospitalière, OR, Odds ratio, RAMQ, Régie de l'assurance-maladie du Québec, RR, Risk ratio