Relapse occurrence in women with multiple sclerosis during pregnancy in the new treatment era.

OBJECTIVE

To determine the rate of relapse occurrence during pregnancy and postpartum.

METHODS

In a cross-sectional study using the national multiple sclerosis (MS) registry, pregnant women with relapsing MS were identified. Data on demographics, clinical characteristics, and disease-modifying therapies (DMTs), including washout periods, were collected. Timings and durations of relapses were extracted. A multivariate logistic regression was used to assess the relationship between relapses and prior use of different DMTs.

RESULTS

Completed data were available for 99 pregnancies (87 patients). Mean age and mean age at onset were 31.8 ± 5 and 24.4 ± 5.6 years, respectively, while the mean disease duration was 7.4 ± 4.6 years. Most pregnancies (89.9%) occurred in patients who were on DMTs in the year preceding pregnancy with a mean treatment duration of 63.4 ± 29 months. The rates of occurrence of relapses during pregnancy and postpartum were 17.2% and 13.7%, respectively. Most of the relapses occurred during the first (n = 6) and third (n = 7) trimesters. Rate of relapse was highest among patients receiving natalizumab and fingolimod before pregnancy. A longer washout period was significantly associated with relapse occurrence.

CONCLUSION

The relapse occurrence during pregnancy is higher than the previously published rates. The use of high-efficacy therapies with long washout periods before conception was associated with an increased risk of relapses during pregnancy. Postpartum relapse occurrence was similar to that in previous reports.