Our aim is to add to the limited existing prospective data on IL-1 inhibitor use in pregnancy.

Data were obtained from the Organization of Teratology Information Specialists Autoimmune Disease in Pregnancy Project, a prospective cohort study of pregnancy outcomes in the USA and Canada. Eligible women were enrolled prior to 19 weeks' gestation between 2004 and 2017. Outcomes were obtained by maternal interview and medical record abstraction.

Five pregnancies with anakinra exposure were identified, all resulting in full-term singleton live births with no major or long-term complications. Three maternal subjects used anakinra for adult-onset Still's disease and two for systemic JIA. For all individuals who discontinued anakinra, some amount of steroid medication was necessary for treatment of disease flare. Two maternal subjects developed oligohydramnios, one also with pregnancy-induced hypertension. Two women had Caesarian sections, one medically indicated and one scheduled. One infant had low birth weight, but follow-up records indicated normal adjusted weight at 1 year. Three women successfully breastfed their infants, at least two of whom continued anakinra while breastfeeding.

Anakinra was used successfully in five full-term pregnancies; however, two subjects developed oligohydramnios, a process that can be linked to fetal renal anomalies. Given previously reported cases of congenital renal anomalies associated with both antenatal anakinra use and maternal hyperthermia, the relationship between maternal IL-1 inhibitor use, uncontrolled maternal febrile disease and fetal outcomes should be further explored.