Immune System Effects in Children Born to Women With Multiple Sclerosis Treated With Monoclonal Antibody Therapy During Pregnancy

The goal of this observational study is to learn about consequences for the child when the mother is treated with rituximab (or other monoclonal CD-20 antibodies) before or during pregnancy. The main questions it aims to answer are: * Is the infant's immune system effected with lower levels of B-cell markers, higher rates of infections or poor vaccine response? * Are the monoclonal CD20-antibodies fully eliminated in women treated within 6 (12) months prior to conception? Participants will: * At the time of clinical routine blood sampling (at the end of each trimester) the becoming mother will give some additional blood samples for analysis of drug concentration * Within the first year postpartum the child will leave a blood sample to detect antibodies induced by vaccination or infections * Within our routine contacts with the participant (mother) will be asked about infections in both the mother and the child