Background and aims
Limited data are available on the consequences of prenatal exposure to vedolizumab and ustekinumab. We aimed to compare the safety of vedolizumab and ustekinumab with that of anti-TNF, in pregnant women with inflammatory bowel diseases (IBD).

Methods
Using nationwide, comprehensive data of the EPI-MERES registry, we identified pregnancies in women with IBD in France, exposed to anti-TNF, vedolizumab, and ustekinumab between 2014 and 2021. We compared pregnancy outcomes and complications in the offspring according to treatment exposure during pregnancy. We applied a propensity score matching for maternal, IBD, and pregnancy characteristics.

Results
398 pregnancies exposed to vedolizumab were compared to 1,592 pregnancies exposed to anti-TNF; 464 pregnancies exposed to ustekinumab were compared to 1,856 pregnancies exposed to anti-TNF. Overall, compared to anti-TNF, neither vedolizumab nor ustekinumab were associated with increased risks of abortion, caesarean section, stillbirth, preterm birth, serious infections, malignancies, or congenital abnormality in children. Women exposed to ustekinumab had an increased risk of small for gestational age births.

Conclusions
Overall, the safety of vedolizumab and ustekinumab compared to anti-TNF use during pregnancy is reassuring. Further studies are needed to confirm these findings.