MS treatment during pregnancy found safe for babies’ brain growth

Using disease-modifying treatments shortly prior to or during pregnancy does not seem to increase the risk of neurodevelopmental disorders in exposed children, according to a real-world study of mothers with multiple sclerosis (MS).

Still, sphingosine-1-phosphate (S1P) receptor modulators, which include therapies such as Gilenya (fingolimod), Mayzent (siponimod), and Ponvory (ponesimod), were linked to an increased risk of major birth defects.

“Mothers can be reassured that no significantly increased risk was identified for neurodevelopmental disorders,” but “counseling about the risk of rebound relapse should be weighed against probability of fetal [problems] with S1PR modulators,” researchers wrote.

The study, “Association of Neurodevelopmental Disorders and Congenital Anomalies With Prenatal Multiple Sclerosis Treatment — Real-World Historical Cohort Study,” was published in Clinical Pharmacology & Therapeutics.

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MS is more common in women than in men and often occurs during childbearing years. While many women discontinue their disease-modifying treatments during pregnancy, some may need to continue their treatment due to severe symptoms. Others may have unplanned pregnancies while on treatment.

However, there is limited data about how exposure to these treatments may affect how children develop in the womb and after birth.

To address this gap, a team of researchers in Israel assessed whether using these treatments before or during pregnancy is linked to neurodevelopment disorders, which affect the development and function of the brain, or major congenital anomalies, which are structural or functional defects present at birth.

They reviewed medical records from all children included in the Clalit Health Services in Israel who were born to mothers with MS between 2005 and 2023.

Out of 1,374 children fulfilling this criteria, 890 were not exposed to any MS disease-modifying treatments before birth. The remaining 484 were exposed to one or more of these treatments at some point between six months before conception and birth.

The most common were interferon-based therapies, with 237 children being exposed to these medications. Other therapies included glatiramer acetate (sold as Copaxone and others), monoclonal antibodies such as Ocrevus (ocrelizumab), fumarate therapies such as Tecfidera (dimethyl fumarate) and Bafiertam (monomethyl fumarate), and S1P receptor modulators.

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Over a median of 6.25 years, 297 children were diagnosed with a neurodevelopmental disorder, such as autism, emotional disturbance, and developmental issues related to coordination, speech, or language.

But statistical analyses did not find a significant association between exposure to disease-modifying treatments and a higher risk of neurodevelopmental disorders. This remained consistent after adjusting for factors that could influence neurodevelopment, such as the mother’s age and socioeconomic status, and when accounting only for exposure during pregnancy.

The researchers also looked at major congenital anomalies during the first two years of life. In total, 50 children were diagnosed with a major birth defect, including 33 children who were not exposed to any disease-modifying treatments before birth. Overall, the rate was similar in children who were not exposed and those who were.

However, children exposed to S1P receptor modulators during the months of pregnancy had a significantly higher risk of major congenital anomalies. In that group, 2 out of 25 children (8%) had a major birth defect. However, confidence intervals were wide, meaning the estimate was imprecise due to the small sample size.

These S1P receptor modulators “are not prescribed to women planning pregnancy, and effective contraception is recommended to all women of childbearing age during and at least [two] months after their discontinuation,” the researchers wrote.

They noted, however, that exposure can still happen, “for example, when unplanned pregnancies occur,” in which case “women are informed about the potential risk of treatment-related developmental abnormalities and are intensively screened.”

While the study found no evidence that prenatal exposure to most disease-modifying treatments increases the risk of neurodevelopmental disorders, which is reassuring for mothers with MS, more studies “are needed to establish robust conclusions with regard to the safety of MS treatments in pregnancy,” the researchers concluded.