Certain medications for multiple sclerosis, classified as monoclonal antibodies, which can be taken while breastfeeding may not affect the development of a child during the first three years of life, according to a new study. The study examined four monoclonal antibodies for MS: natalizumab, ocrelizumab, rituximab, and ofatumumab.

MS is a disease in which the body’s immune system attacks myelin, the fatty white substance that insulates and protects the nerves. Symptoms may include fatigue, numbness, tingling, or difficulty walking.

For the study, researchers at Ruhr University in Bochum, Germany, used the German MS and Pregnancy Registry to identify 183 infants born to mothers taking monoclonal antibodies while breastfeeding. Of this group, 180 had mothers with MS and three had mothers with neuromyelitis optica spectrum disorder. NMOSD is also a demyelinating disease, but is rare and specifically affects the optic nerve, spinal cord, or brain. These infants were compared to another 183 infants, matched for exposure to MS medications shortly before or during pregnancy, and born to mothers with the same diseases who did not take monoclonal antibodies while breastfeeding. 

Of those exposed to MS medications, 125 were exposed to natalizumab, 34 to ocrelizumab, 11 to rituximab, and 10 to ofatumumab. Two infants were first exposed to natalizumab and then ocrelizumab. One infant was exposed to rituximab and then ocrelizumab. The first exposures to the medications through breastfeeding ranged from the day the child was born to the ninth month of life. Infants were breastfed for an average of five-and-a-half months while their mothers took these medications.

For all infants, researchers then examined the number of hospital stays, antibiotic use, developmental delays, such as problems with social and fine motor skills, delayed speech development, and the infants’ weight at follow-up visits during the first three years of life.

After comparing infants exposed to the medications versus infants not exposed, researchers found no differences in their health or development. The authors said their data showed infants exposed to these medications through breastfeeding experienced no negative effects on health or development within the first three years of life.

The limitation of the study was only about a third of the infants were followed for the full three years. Therefore, the results for the third year of life are less meaningful than for years one and two.

The study will be presented at the American Academy of Neurology’s 76th Annual Meeting taking place April 13-18, in person in Denver and online.