A case report of two systemic lupus erythematosus pregnancies with early placental exposure to belimumab: Case report with review.

Since its approval for the management of systemic lupus erythematosus (SLE), belimumab has been widely used. However, its pregnancy safety profile has been underinvestigated. We present the pregnancy outcomes of two cases of early placental exposure to belimumab and summarise the pregnancy outcomes in previous reports regarding placental exposure to belimumab. Case 1 describes a 27-year-old woman with an 18-year history of SLE and lupus nephritis class III. We introduced belimumab 19 months prior to conception to control her proteinuria and discontinued its use at 5 weeks and 5 days of gestation. Her lupus activity was stable throughout pregnancy, and at 37 weeks and 1 day of gestation, she delivered a healthy girl with no anomaly. At delivery, the girl was small for gestational age, but at the 1-year follow-up, there was no delay in her growth or any serious infection. Case 2 describes a 32-year-old woman with a 15-year history of SLE. We introduced belimumab 9 months prior to conception and discontinued its use at 7 weeks and 1 day of gestation. Although her lupus was well controlled without belimumab, a missed abortion occurred, which was possibly due to foetal factors. Although there is accumulating data on the safety of belimumab use during pregnancy, it seems necessary to cautiously use this medication in pregnant women, until further analyses are conducted.