Outcomes in patients stopping biologic during the first trimester of pregnancy: a retrospective monocentric study

Guidelines recommend continuing biologics during pregnancy but patients remain concerned about foetal drug exposure. For women in sustained remission, discontinuing biologics before active placental transfer (≈GW20) may represent a compromise. We evaluated disease activity and pregnancy outcomes in this situation and measured biologic concentrations in cord blood to estimate foetal exposure.

We conducted a retrospective study including all IBD pregnancies followed at the University Hospital of Liege (2010-2023). Disease flare was defined as the need for corticosteroids, start/resumption of biologics, or surgery. Preterm birth, caesarean section, low birth weight were recorded. Additionally, drug levels in paired maternal-cord samples (n = 5) were prospectively measured at delivery in women stopping biologic between GW12-20.

We analysed 185 pregnancies in 143 women. Ninety pregnancies began under biologics: 80 (88.9%) discontinued before GW20 and 10 (11.1%) continued treatment. Disease flare occurred in 14/80 (17.5%) and 4/10 (40%), respectively. Among the 80 who discontinued before GW20, 16/80 (20%) preterm births, 31/80 (39%) caesarean sections and 10/80 (12.5%) low birth weight were reported. Stopping treatment before GW20 was not associated with an increased risk of disease flare (p value = .11). Low residual levels were detected in cord blood in one ustekinumab-exposed case.

Discontinuing biologic therapy before GW20 in women with IBD in remission was associated with a relapse rate of 17.5%, suggesting this approach may be a safe option to minimise foetal drug exposure without significantly increasing relapse risk. Larger, prospective studies are warranted to validate these findings and refine treatment strategies during pregnancy.