Biologics and/or thiopurine therapy for IBD should not be stopped in pregnancy according to the authors of a US study that found no evidence of harm but a higher risk of adverse pregnancy outcomes associated with higher disease activity.

The prospective PIANO study followed up 1431 pregnancies in women with IBD and found that exposure to biologics (n=642), thiopurine (n=242)  or a combination (n=227) was not associated with an increase in congenital malformations, spontaneous abortion, preterm birth, low birth weight, or infections in the first year of life.

However there was an increased risk of spontaneous abortion (HR 3.41, 95% CI 1.51-7.69) seen with higher disease activity, which was also associated with an increased risk of preterm birth and infant infection.

There was no evidence of any adverse outcomes in in developmental milestones in infants exposed to IBD drugs followed for up to 48 months, according to the findings published in Gastroenterology.

The study authors, led by Professor William Sandborn of the University of California, said the findings backed the recent AGA Clinical Care Pathway recommendation to continue biologic therapy through pregnancy.

“There is no strong rationale to withhold biologic therapy in any pregnant IBD patient based on available evidence from PIANO and other international studies,” they wrote.

“Overall, these findings emphasize the need to control disease activity during pregnancy as well as the lack of harm associated with the use of biologic and thiopurine therapy.”

The study investigators noted that European guidelines still suggested stopping biologics as early as 22 weeks gestation, despite 10-25% increased risk of disease flare.

“Practitioners have generally become more comfortable using biologics in the first trimester of pregnancy. However, as significant placental transfer occurs, there have been lingering concerns about infection and altered immune development in infants when biologics are used in the third trimester.”

“Practitioners should continue biologic and/or thiopurine therapy throughout pregnancy given no evidence of increase in harm from drug exposure and the clear association of active disease with adverse events,” they advised.

In the study, women with ulcerative colitis had significantly increased disease activity compared to those with Crohn’s Disease during each trimester, “possibly due to production of pro-inflammatory cytokines by the placenta that activate UC, or because UC activity is undetected and undertreated in pregnant women,” the authors said

Women who were unexposed to biologics or immunomodulators were more likely to flare during the course of pregnancy.

“This demonstrates the need for therapy to maintain control of inflammation throughout pregnancy,” they concluded.

The recent AGW 2020 virtual meeting featured several small Australian studies of pregnancy outcomes in women with IBD. In one Queensland study of 44 pregnancies, 70% of women continued with medical treatment during pregnancy, and 47% flared during pregnancy. Despite this there were no major adverse obstetric or neonatal outcomes.

Another study involving 18 pregnant women with active IBD showed that induction treatment with anti‐TNFα appeared to be effective for inducing remission during pregnancy, and no serious infant infections were seen.