Maternal use of 5-aminosalicylates in early pregnancy and congenital malformation risk in the offspring

Abstract

Objective. Most previous studies have failed to demonstrate any effect of maternal use of 5-aminosalicylates (5-ASA) on malformation risk, but the number of infants studied have, in most cases, been low. The objective of the study was to get data from a large study with prospectively ascertained exposure information. Material and methods. The study was based on data in the Swedish Medical Birth Register (1996–2011) where identification of maternal drug use is made from midwife interviews in early pregnancy. The presence of congenital malformations was ascertained from three national registers. Adjusted odds ratios were calculated by the Mantel-Haenszel methodology. Results. Among 1,552,109 women, 3651 with 3721 infants had reported the use of 5-ASAs in early pregnancy. The risk of a major malformation was increased (1.37, 95% confidence interval = 1.17–1.62) and still more for a cardiovascular defect (1.74, 1.37–2.22). This effect seemed to be influenced by concomitant use of systemic glucocorticosteroids or immunosuppressants but some confounding by indication may also exist. There was no marked difference between the four 5-ASA drugs studied. Conclusions. Infants born of women who use 5-ASA drugs in early pregnancy have an increased risk of a congenital malformation, notably a cardiovascular defect. This could be a drug effect or an effect of an active inflammatory bowel disease.