Impact of disease-modifying therapies on pregnancy outcomes in multiple sclerosis: a prospective cohort study from the German multiple sclerosis and pregnancy registry.

Background: In recent decades, relapsing remitting multiple sclerosis (MS) became more treatable through new disease-modifying therapies (DMTs). Identifying safe treatments with minimal fetal risks for family planning is needed.

Methods: In this prospective cohort from the German MS and Pregnancy Registry (DMSKW), we analyzed pregnancy and neonatal outcomes in MS-patients using descriptive statistics and logistic/linear regression models to compare DMT-exposed pregnancies to DMT-unexposed pregnancies.

Findings: In 2885 DMT-exposed and 837 DMT-unexposed pregnancies, exposure was not associated with spontaneous abortions, preterm births or major congenital anomalies (MCAs). Severe infections were rare, but more frequent in the Fumarates-group (11/395: 2.8% vs. 8/837 unexposed-group: 1.0%, p-value: 0.03). Antibiotic-use was associated with 2nd-trimester (OR: 2.47, CI: 1.47, 4.05, p-value: <0.001), 3rd-trimester Natalizumab-exposure (OR: 1.75, CI: 1.15, 2.63, p-value: 0.01), and anti-CD20-exposure (OR: 2.16, CI: 1.41, 3.29, p-value: <0.001). Birthweight was significantly reduced in the Sphingosine-1-phosphate-group (β: -132 g, CI: -205, -60, p-value: <0.001), and 3rd-trimester Natalizumab-subgroup (β: -74 g, CI: -138, -9.4, p-value: 0.02). Small for gestational age (SGA) neonates were common in the Sphingosine-1-phospate- (OR: 1.65, CI: 1.07, 2.50, p-value: 0.02) and anti-CD20-group (OR: 1.54, CI: 1.01, 2.32, p-value: 0.04), and also the entire cohort (651/3459: 18.8%), exceeding the general German population rate (10%) (p-value: <0.001).

Interpretation: We observed an increased SGA risk, especially following highly-effective DMTs, although the pathomechanisms remain unclear. More research is needed on infection risks and MCAs, perhaps by linking different registries.

Funding: The DMSKW is partly supported by Almirall, Biogen, Hexal, Merck, Novartis, Roche, Sanofi Genzyme, Teva Pharma and Viatris.