Successful Pregnancies with Thiopurine-Allopurinol Co-Therapy for Inflammatory Bowel Disease

Background: Thiopurines are an effective treatment for moderate to severe inflammatory bowel disease [IBD] and can be used safely in pregnancy. Combining allopurinol with a lower dose of thiopurine can improve clinical efficacy and bypass some adverse reactions associated with thiopurine monotherapy. Data on allopurinol in pregnancy are scarce. We report on a total of 13 cases where thiopurine and allopurinol co-therapy was used successfully to manage IBD during pregnancy without attributable adverse fetal effects. Methods: Patients were retrospectively identified at our two hospitals, one in the UK and one in Australia, using local IBD databases. Data regarding pregnancy and fetal outcomes including in utero fetal ultrasound scans, APGAR scores, fetal birthweights and neonate checks were collected from patient notes. Results: We identified 12 women with a total of 13 pregnancies treated with co-therapy before conception and for the duration of pregnancy. There were no miscarriages or spontaneous pre-term deliveries. There were 14 live births [seven vaginal deliveries; six caesarean sections]. Except for a primagravid twin pregnancy complicated by pre-eclampsia and twin-to-twin transfusion syndrome requiring caesarean section at 25 weeks, there were no low birthweight [< 2.5 kg] babies born and the APGAR scores of all babies were normal. No congenital malformations were identified. Conclusions: Adverse pregnancy outcomes attributable to thiopurine and allopurinol co-therapy were not detected in our case series. Our study provides reassurance for clinicians and patients who wish to continue the thiopurine-allopurinol co-therapy combination before conception and during pregnancy to maintain remission of IBD.