The first biologic authorized for systemic lupus erythematosus (SLE) up to this date, belimumab, is currently not recommended for use during pregnancy due to lack of data. Provided that the health of the child begins with the health of the mother, pregnant patients face the dilemma of cessation or continuation of belimumab. If belimumab is stopped, there will be a risk of SLE flare and its consequences for the mother and the foetus. Continuation is also not optimal because of the lack of knowledge on safety for use during pregnancy.

To compare the reported foetal outcomes in SLE patients who stopped scheduled belimumab within the first trimester (group A) and those who continued scheduled belimumab during the first trimester or thereafter (group B).

All belimumab-exposed pregnancy-related reports were extracted from the EudraVigilance (EV) database until March 11th, 2021. After case review, repeated cases, uninformative reports, non-medical elective abortions and foetal chromosomal abnormalities were excluded. Included pregnancies were divided into two groups (group A and B, as described above). Foetal outcomes were divided into live birth or foetal death (due to miscarriage or stillbirth) and were compared between both groups. Furthermore, neonatal outcomes, such as reporting rates of preterm birth, low birth weight and major congenital malformations were compared.

No statistical difference in foetal death was observed between group A and B (reported numbers (%) = 32 (46.4) and 11 (52.4), respectively). Odds ratio (OR, [95% Confidence Intervals (CIs)]) of foetal death in group B compared to group A was 1.27 [0.48, 3.32]. Reporting rates of preterm birth and low birth weight were higher - though not statistically different - in group A.

The positive results of our study are supportive for the continuation of belimumab during pregnancy. Since the analysis is based on spontaneous reports/retrospective data, additional studies are needed to confirm the results.