One in three women with IBD believe every IBD drug is harmful in pregnancy. The cost of that belief shows up as flares, preterm births and babies born small for gestational age.

Mette Julsgaard, Associate Professor at Aarhus University Hospital and Director of Denmark's National Centre for Preconception and Pregnancy in Autoimmune Diseases, was a co-author of the 2025 global consensus statement on pregnancy in IBD. With Pradeep Mundre she works through the period before conception: what active disease does to fertility in men and women, what to check at the preconception visit beyond disease activity, and why the stop list is short (JAK inhibitors, S1P receptor modulators and, in women, methotrexate).

Then a drug by drug run through of pregnancy and breastfeeding, including why the biologics reach breast milk at under 1 % of maternal blood levels, as well as the recommendation for the use of aspirin for patients with IBD during pregnancy.

Part two covers flares, surgery, delivery and vaccination and will be published on the 2nd of September 2026.

Further reading:

• Global consensus statement on the management of pregnancy in inflammatory bowel disease](https://doi.org/10.1136/gutjnl-2025-336402))
• Fertility, the "large British study"
• Ovarian reserve, the "two small studies". Study 1 Study 2](https://doi.org/10.1016/j.crohns.2012.03.003))
• What predicts a flare in pregnancy
• Methotrexate in men
• Endoscopy in pregnancy, the AJG article Mette recommends
• Calprotectin
• PIANO registry
• ECCO Guidelines on Sexuality, Fertility, Pregnancy, and Lactation
• Aspirin