Safety of Tioguanine During Pregnancy in Inflammatory Bowel Disease

Background and Aims: Conventional thiopurine [azathioprine and mercaptopurine] treatment during pregnancy in patients with inflammatory bowel disease [IBD] is considered to be safe; however data on the safety and teratogenicity of the non-conventional thiopurine tioguanine [TG] in pregnant IBD patients are lacking. We aim to describe the safety and teratogenicity of TG treatment during pregnancy in IBD patients. Methods: This was a retrospective, multicentre descriptive case series of female IBD patients using TG during pregnancy. Data on disease and medication history, pregnancy complications, pregnancy outcome, mode of delivery, preterm birth, birthweight, congenital abnormalities, laboratory signs of myelosuppression or hepatotoxicity, and 6-thioguaninenucleotide [6-TGN] concentrations in mother and neonate were collected. Results: In all, 13 patients [77% Crohn's disease, 23% ulcerative colitis] used TG [median dose 18 g/day] during pregnancy; 19 pregnancies, including 1 twin pregnancy, were included. Spontaneous abortion occurred in three pregnancies. In 7 of the 16 ongoing pregnancies a caesarean section was performed. One neonate had a mild congenital abnormality [distal shaft hypospadias]. In the singleton pregnancies, the median birthweight was 3410 g at a median of gestational age of 39 weeks. No preterm birth [< 37 weeks] or low birthweight [< 2500 g] was observed in the singleton newborns. In the twin pregnancy an induction of labour was performed at 35 + 1 weeks of gestation because of pre-eclampsia. Both neonates had a low birthweight. Conclusions: This relatively small case series supports safe use of TG in pregnant IBD patients. Still, consideration should be given to the indication and continuation of TG during pregnancy.