Background and Aims

Belimumab (BEL) is an anti-BLyS monoclonal antibody approved for SLE treatment. Few data are available on its administration before or during pregnancy. The aim of this study is to describe pregnancies in SLE patients who have discontinued BEL either at preconception or at positive pregnancy test or during pregnancy.

Methods

Data of SLE prospectively-followed pregnancies (2014-2020) in SLE patients treated with BEL in 3 Italian centers where retrospectively collected, focusing on disease activity and pregnancy outcome. The use of BEL during pregnancy was agreed with the patient during the preconception counseling.

Results

Fourteen SLE pregnancies were analyzed (mean age at conception 32.9±5.4 years; 79% spontaneous, 71% primigravidae; 79% planned). BEL (12 intravenous, 2 subcutaneous) was stopped in 2 cases preconceptionally, in 8 at positive pregnancy test and in 4 during pregnancy (2 at 11^th week, 1 at 22^nd, 1 at 24^th) (Table 1). Other treatments during pregnancy were: prednisone (13); antimalarials (12); azathioprine (6); calcineurin-inhibitors (5); low-dose acetylsalicylic acid (11); low molecular weight heparin (9).

At preconception visit, the mean SLEDAI was 2.9±2.6.

Three flares occurred in the 3^rd trimester, all in patients who suspended BEL at positive pregnancy test.

Live-births were 93%; 1 late miscarriage occurred. One eclampsia (hesitated in perinatal death) and 1 pre-eclampsia occurred.

No malformations were recorded. Two newborns were hospitalized in Intensive Care Unit (milk protein intolerance; desaturation).

Conclusions

This small series suggests that BEL might be an option for SLE patients planning a pregnancy (as other biological drugs in different rheumatologic diseases), although more data are needed.