Maternal mesalazine-induced neonatal gastrointestinal bleeding

Ulcerative colitis often develops in the reproductive age women and can cause exacerbation by pregnancy. Mesalazine (5-aminosalicylic acid) is recommended as a safe anti-inflammatory drug during pregnancy. However, maternal mesalazine is transferred to the fetus through the placenta and may cause allergic events. A pregnant woman with severe ulcerative colitis was treated with a dose of mesalazine 4,000 mg/day from early gestation to delivery. Immediately after birth, the preterm neonate vomited bloody contents and discharged massive gross haematochezia. Serum concentrations of mesalazine and its main metabolite were high in the mother and the umbilical cord. Faecal eosinophils and drug-induced lymphocyte stimulation test suggested possibility that sensitisation with mesalazine in utero caused allergic enterocolitis like food protein-induced allergic proctocolitis. Maternal mesalazine has a potential of fetal sensitisation and cause allergic disease.