In recent decades, many new disease-modifying therapies (DMT) have been approved for treating MS. Although MS primarily affects women of childbearing age, until now, there has been limited safety data on how these drugs affect pregnancy.
In the current study, researchers analyzed data from the German MS and Pregnancy Registry. A total of 2,885 DMT-exposed and 837 DMT-unexposed pregnancies were included in the analysis. Most women only received medication during their first trimester.
DMTs in the study included interferons, glatiramer actate, dimethyl fumarate, teriflunomide, S1P modulators (fingolimod, ponesimod), alemtuzumab, natalizumab, anti-CD20 antibodies (rituximab, ocrelizumab, ofatumumab) and cladribine.
Ultimately, the researchers found that most DMTs for MS were not linked to statistically significant increases in spontaneous abortions, premature births, or major congenital defects.
They found, however, that taking DMTs was linked to an increased risk of low birth weight relative to pregnancy duration. Whereas low birth weight occurs in around 10% of all births in Germany, 18.8% of babies with prenatal exposure to DMT were born at a below-average weight. The same was true for 17.6% of babies born to mothers with MS who didn’t receive any medication.
The researchers noted that the association was particularly pronounced with S1P modulators and anti-CD20 antibodies, which increased the risk of low birth weight by 27.4% and 24.1%, respectively.
The researchers concluded that while a link was observed between DMTs and low birth weight risk, the underlying mechanisms remain unclear. They also noted that more research is needed on infection risk and major congenital anomalies, which may be conducted by linking different registries.
