Thiopurine Therapy for Inflammatory Bowel Disease During Pregnancy Is Not Associated with Anemia in the Infant

Thiopurine exposure throughout pregnancy in patients with inflammatory bowel diseases (IBD) is common and teratogenically safe. Late consequences of in utero exposure to thiopurines and its metabolite, 6-thioguanine nucleotides (6-TGN), such as neonatal and infant anemia are still disputed.

To evaluate whether 6-TGN exposure during pregnancy influences anemia in infants at 1 year of life.

A comparative observational study was performed between 2009 and 2015 at a multidisciplinary IBD clinic dedicated to pregnant women. The hemoglobin level and signs of anemia between 9 and 15 months after birth of infants born to women exposed to thiopurines throughout the entire pregnancy was compared to infants of women with no thiopurine exposure during pregnancy.

Altogether, 34 patients, 21 in the study group and 13 in the control group, were included. The median duration of maternal thiopurine exposure prior to pregnancy was 24 months (range 12–72 months), and median dosage was 100 mg (range 50–175 mg). Maternal IBD activity, infants’ iron supplementation, and iron deficiency diagnoses were similar between both groups. The infants’ mean hemoglobin level (gr/dL) in the thiopurine-exposed women versus the control group was 11.48 ± 0.8 versus 11.54 ± 0.6, respectively, p = 0.81. The composite risk of any sign of infant anemia was numerically higher in the thiopurine-exposed women, 10 (47%), compared to non-exposed women, 3 (23%), p = 0.17. The mean corpuscular volume, red cell distribution width, white blood cell, and platelet counts were similar among groups.

Thiopurine therapy during pregnancy in women with IBD is safe for long-term neonatal outcomes; still large-scale confirmatory studies are required.