(HealthDay News) — For pregnant women with multiple sclerosis (MS), natalizumab exposure is associated with an increased risk of spontaneous abortion (SA), and longer periods of natalizumab washout predict relapse during pregnancy, according to two studies published online Feb. 7 in Neurology.
Emilio Portaccio, M.D., from the IRCCS Don Gnocchi Foundation in Florence, Italy, and colleagues examined fetal risk after pregnancy exposure to natalizumab in women with MS. Data were obtained for 92 pregnancies occurring between 2009 and 2015 in 83 women with MS treated with natalizumab. The researchers found that natalizumab exposure correlated with SA in the multivariable analysis (odds ratio, 3.9). The rate of SA (17.4 percent) was within the estimates for the general population, as was the rate of major congenital anomalies (3.7 percent).
In a second study, Portaccio and colleagues examined the risk of disease reactivation during pregnancy after suspension of natalizumab during pregnancy. Data were included for 74 pregnancies in 70 women that resulted in live births, and were compared with 350 previously reported pregnancies. During and after pregnancy, the relapse rate was significantly higher in women treated with natalizumab. The only predictor of relapse occurrence during pregnancy was longer natalizumab washout period, in multivariable analysis (P = 0.001). There were correlations for relapses during pregnancy and early reintroduction of disease-modifying drugs with relapses in the postpartum year (P = 0.019 and 0.021, respectively).
“These studies provide information that is highly relevant to decisions surrounding the use of natalizumab in women considering pregnancy,” write the authors of an accompanying editorial.
Several authors from both studies disclosed financial ties to the pharmaceutical industry.