To explore processing speed (PS) during pregnancy in people with multiple sclerosis (pwMS) and healthy women (HCW).

PS is a very sensitive measure of global cognitive performance. It is one of the most used neuropsychological measures in people with multiple sclerosis (pwMS), as PS impairment is the earliest and most prevalent cognitive disfunction in pwMS. It is also regarded as a sensitive biomarker for cognitive integrity. 

During pregnancy, literature reports an impairment in PS in late pregnancy and puerperium.

We consecutively included 30 pregnant pwMS and 37 HCW between 2018 and 2022. Measurements were collected using the written version of the Symbol Digits Modalities Test (SDMT) at first, second and third trimesters of pregnancy. Statistical analysis was performed with Friedman Test after normality testing. The study received local IEC approval.

PwMS and HCW were similar in age (PwMS mean(SD) 34,57(5,1) vs HCW 33,35(3,9)) and educational level (PwMS 14,9(3,5) vs HCW 16,2(2,1)). 

SDMT mean score for the first trimester in pwMS was 57 (SD 8.7); second trimester 54 (SD 8,5) and third trimester 54 (SD 10,4). All scores were within their normative population range. In HCW, first trimester mean score was 60,27 (SD 9,4); second trimester 60 (SD 7.3) and third trimester 59 (SD 6.7).  No statistically differences were found in any of the three trimesters SDMT´s scoring either for PwMS or HCW.

Our results showed a stable PS performance during the three trimesters of pregnancy in MS, similary to healthy control pregnant. Unlike previous literature, our data does not support a decreased performance in PS tasks in late pregnancy in MS patients