- Natalizumab is usually discontinued in women with multiple sclerosis well before pregnancy due to the risk of miscarriages and possible congenital anomalies.
- Early discontinuation and a delay in re-institution of the treatment appears to be associated with a higher risk of relapses.
- The risk of congenital abnormalities due to the exposure of natalizumab during early pregnancy is not very clear.
Two studies published in the Neurology evaluated the maternal and fetal consequences of stopping the monoclonal antibody natalizumab in women with multiple sclerosis either well before pregnancy or within the first few days of the pregnancy. The studies evaluated 92 pregnancies.
In the study that evaluated the maternal risks:
- The relapse rate of multiple sclerosis during and after the pregnancy was three times higher (37%) in the women that discontinued natalizumab than those who never received it (10%).
- The relapses were particularly more common during the first three months of pregnancy and following delivery.
- The relapses were more common if natalizumab was stopped earlier during pregnancy.
- The number of relapses following the delivery appeared to be lesser with the early re-introduction of disease modifying drugs following the delivery.
- The rate of spontaneous abortions (miscarriage) was four times higher than what occurred in women with multiple sclerosis who received interferon or no treatment during pregnancy. The risk of 17.4% that occurred in these women was, however, similar to that in the general population (14%).
- The risk of congenital abnormalities in the babies of 3.7%, was again similar to that of the general population.
- Exposure to natalizumab and interferon-β was associated with lower length and weight of the babies.
About NatalizumabNatalizumab is used for the treatment of multiple sclerosis in those patients who do not respond to or are unable to tolerate other medications. Multiple sclerosis is a condition where antibodies attack the covering of nerves, eventually resulting in nerve damage.
- Portaccio E et al. Pregnancy decision-making in women with multiple sclerosis treated with natalizumab I: Fetal risks. Neurology Feb 2018. DOI: 10.1212/WNL.0000000000005067
- Portaccio E et al. Pregnancy decision-making in women with multiple sclerosis treated with natalizumab II: Maternal risks. Neurology Feb 2018. DOI: 10.1212/WNL.0000000000005068