Neurofilament light chain levels in pregnant multiple sclerosis patients: a prospective cohort study

Background and purpose Neurofilament light chain is a cytoskeletal protein of neurons. Its levels are increasingly recognized as measures of neuroaxonal damage. The aim of this study was to explore serum neurofilament light chain (sNfL) levels in multiple sclerosis (MS) patients and healthy controls during pregnancy and puerperium. Methods This was a prospective, longitudinal, single‐center study. sNfL concentration was assessed using a highly sensitive single‐molecule array during pregnancy and in puerperium, in a cohort of 39 pregnant patients with relapsing multiple sclerosis (P‐MS). Twenty‐one healthy pregnant women (HPW) served as a control group. Eight P‐MS suffered relapses during pregnancy (P‐MS‐R) in the first or second trimesters. Results No differences in pregnancy and delivery data were observed between P‐MS and HPW. P‐MS showed higher sNfL values than HPW in the first trimester, independently of the presence (P = 0.002) or not (P = 0.02) of relapses during pregnancy. However, in the third trimester, only P‐MS‐R showed higher sNfL values than HPW (P = 0.001). These differences extended to the puerperium, where P‐MS‐R showed higher sNfL values than those with no relapses during gestation (P = 0.02). Conclusion These data strongly suggest that sNfL levels reflect MS activity during pregnancy. Additionally, the absence of relapses during pregnancy may have a beneficial effect on neurodegeneration during puerperium.