Importance of planning pregnancies with Multiple Sclerosis (MS)

June 04, 2014

A recent study addressed the outcomes of pregnancy in women with MS who were taking fingolimod (Gilenya). Of 66 pregnancies on the medication, 41 attempted to carry the pregnancy to term. 26 of the 41 had healthy newborns. There were, 9 miscarriages, 24 elective abortion, 4 ongoing pregnancies and 1 with an unknown outcome. Of the elective abortions, four were for fetal malformations. There were 5 cases with abnormal fetal development in the 66 pregnancies. Poor fetal outcomes were found in 14.6% of the pregnancies. This contrasts with a 3% rate of poor outcomes for most pregnancies.

This paper highlights the importance of care in planning pregnancies in MS. It is now known that women with MS have fewer attacks during pregnancy, but more attacks in the first three months after delivery. Overall, between the 9 months of pregnancy and 3 months after delivery there is no change in the course of the disease. None of the medications for MS are approved for pregnancy. This is primarily because the risks of these medications in pregnancy are largely unknown. Animal studies have been done to explore the risk of these medications in pregnancy, but human studies are impossible to conduct because that would require that hundreds of pregnancies in MS patients on medication would need to be compared with hundreds in those not on medication. In the absence of such data, caution suggests that women should stop the medications when planning pregnancy.

The older medications are large molecules that do not cross over the placenta to the fetus very well. This includes the interferons (Avonex, Betaseron, Extavia, Rebif) and glatiramer acetate (Copaxone). Natalizumab (Tysabri) is actively transported across the placenta after the first trimester. Newer medications such as fingolimod (GIlenya), teriflunomide (Aubagio) and dimethyl fumarate (Tecfidera) are small molecules that are able to cross the placenta on their own. It is important to coordinate pregnancy plans with your physician so that medications can be discontinued at the appropriate time before pregnancy is planned.