Thiopurines (azathioprine (Imurel); 6-mercaptopurine (Purinethol)) belong to the class of immunosuppressants frequently used in treatment of IBD to decrease hyperactivation of the gut immune system characteristic of these pathologies. In women with IBD who wish to become pregnant, maintenance of clinical remission via use of these drugs frequently raises the question of possible harmful effects upon the fetus. Studies carried out on rodents, although they used higher doses than those used in humans, suggested that thiopurines could lead to congenital malformations. Up until now, studies in humans have not corroborated those observations nor shown a significant increase in the risk of malformations of the fetus or other pregnancy complications in comparison with the natural risk. Nevertheless, those studies suffered from a lack of statistical strength, as most were carried out on a small cohort of pregnant women. This is what distinguishes the study published in Gut on November 29 2010, which evaluated risk of exposure of the fetus to thiopurines in over 200 pregnant women with IBD. Results from that cohort clearly demonstrate that use of thiopurines during pregnancy does not increase the risk of congenital abnormalities, miscarriages or spontaneous abortions. Association of thiopurines with other treatments (aminosalicylic acids, corticosteroids, anti-TNF) was also evaluated and conclusions were identical. The authors nonetheless emphasize that, despite the high number of patients compared to earlier studies, the cohort was not yet large enough to detect risks occurring at low frequencies. The authors conclude that use of thiopurines for maintaining remission in women with IBD who wish to become pregnant is compatible, and that patients should be reassured as to use of this treatment concomitantly with pregnancy.

Benjamin Bertin

References:

Pregnancy outcome in patients with inflammatory bowel disease treated with thiopurines: cohort form the CESAME study. Coelho, J et al., Gut (Online first, published on November 29, 2010).