Asthma is relatively common in pregnant women, but use of asthma medications in early pregnancy raises concerns about birth defects. Systemic glucocorticoids, such as budesonide and other inhaled steroids, have been linked to cleft lip and cleft palate in animal studies. In the United States, these steroids are classified as category C agents, indicating a teratogenic risk in animals and insufficient data in humans. Kallen and colleagues evaluated data on births in Sweden to identify an association between inhaled budesonide and congenital malformations.

Medical records of women who used inhaled budesonide during early pregnancy were identified from the Swedish Medical Birth Registry database. Information on possible congenital malformations in infants was obtained from coding information recorded at birth and from the Registry of Congenital Malformations. Data from these two sources were thought to identify 80 to 90 percent of all infants with severe malformations.

A total of 2,014 infants of women who had used budesonide in early pregnancy were identified. Most of the women (1,675) had also used other asthma medications. Seventy-five infants in the study group (3.8 percent) had severe congenital malformations, compared with 3.5 percent of infants in the general population. About one half of these infants had major structural defects, such as facial clefts and cardiac defects, and the rest had what are considered mild anomalies. Overall, the incidence of birth defects in the study group was similar to that of the general population.

The authors conclude that use of inhaled budesonide in early pregnancy is unlikely to be associated with a significant teratogenic risk.