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6-MP Is Safe Before and During Pregnancy

The results of this study should help allay fears about use of 6-MP before or during pregnancy.

Use of 6-mercaptopurine (6-MP)/azathioprine in young patients with inflammatory bowel disease (IBD) is complicated by controversy about its possible adverse effects on the fetus when it is taken by the mother or the father. In this retrospective cohort study, researchers reviewed records of 155 patients (79 women; 80% white and Jewish) who had received 6-MP (mean dose, 70 mg) and who had conceived after developing IBD (including patients who had no exposure to 6-MP before pregnancy).

Of 325 pregnancies, 84 occurred among patients who had stopped taking 6-MP before conception, 76 occurred among patients who conceived while taking 6-MP (including 15 women who continued 6-MP until term), and 165 occurred among the patients with no exposure before pregnancy (controls). The incidence of major congenital abnormalities was 2.4% in infants of patients exposed to 6-MP before pregnancy and 4% in infants of controls. There were no statistical differences between groups in rates of spontaneous abortion, abortion secondary to birth defects, minor congenital abnormalities, neoplasms, or serious or recurrent infections among offspring.

Comment: These results should help allay fears about 6-MP use before or during pregnancy. Similar results have been reported in transplant patients and in patients with systemic lupus erythematosus or rheumatoid arthritis. Although patients in this study generally received low doses of 6-MP, when these results are taken together with those from cohorts that received higher doses, 6-MP/azathioprine use appears to be safe during pregnancy.

— Douglas K. Rex, MD

Published in Journal Watch Gastroenterology March 25, 2003

Citation(s):

Francella A et al. The safety of 6-mercaptopurine for childbearing patients with inflammatory bowel disease: A retrospective cohort study. Gastroenterology 2003 Jan; 124:9-17.

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