Breastfeeding, Disease Modifying Therapies (DMTs), and Postpartum Relapse in Multiple Sclerosis

Women with multiple sclerosis (MS) have higher risk of relapse during the postpartum period.  Can exclusive breastfeeding alone prevent relapses? How soon after delivery should disease modifying therapies (DMTs) be reintroduced? Are any DMTs safe to take while breastfeeding? 
 
While disease modifying therapies (DMTs) have been shown generally to reduce relapse rates, none of them are indicated for use during pregnancy and lactation. Therefore, the question of when to restart DMTs postpartum remains a difficult one for physicians counseling MS patients who wish to breastfeed their children.
 
Trying to predict the risk of relapse for any one individual is very difficult. The risk factors for postpartum attacks include the level of disability, the prepregnancy relapse rate, and the relapse rate during pregnancy. But even so, relapse rates in the prepregnancy year and during pregnancy combined only predict 21.5% (49/227) of relapses. The best study is the PRIMS study. They found only relapses before pregnancy, relapses during pregnancy, and EDSS [Expanded Disability Status Scale] as a weak predictor.
 
Reducing the risk of relapse

What can be done to prevent relapses becomes the more important question. Some wonder whether breastfeeding can extend the protection that some women experience during pregnancy.
 
Breastfeeding is not viewed as having a negative effect on the long-term clinical activity of the mother. This is based on the PRIMS study, which found that breastfeeding mothers had reduced relapse rates compared to nonbreastfeeding mothers. This data has been interpreted to mean that breastfeeding can provide protection against relapses. But there’s an apparent bias: women with fewer relapses before and during pregnancy are more likely to choose breastfeeding. So whether breastfeeding actually provides protection remains controversial. 
 
In other studies, use of different DMTs before pregnancy is a significant confounding factor that makes interpretation of the results difficult. Also the study protocols were heterogeneous in that patient-reported breastfeeding rates might have been affected by recall bias.
  
Even if a woman with MS could be classified as belonging to the population with low risk for relapse, this does not mean that she will not relapse. Again, predicting the disease course for an individual patient is difficult. 30% of patients experienced relapses in the postpartum period among those who did not have previous clinical activity. In the end, whether a patient decides to breastfeed (whether for the baby’s benefit or the mother’s) is up to the clinician and the patient interpretation of the data.
 
DMT use immediately after postpartum

For women who choose not to breastfeed, taking DMTs soon after delivery is advisable. The bottom line is there are still no conclusive studies that can provide a simple guide as to what to do with respect to breastfeeding and the use of DMTs in the postpartum period.  It is known that Gilenya, Novantrone, and Tysabri are secreted in milk, but there’s no information regarding Tecfidera. It is less likely that these DMTs will ever be recommended for use in nursing mothers, but more studies are needed.  The decision about whether to breastfeed will depend on many factors, including personal patient choice, level of disability, and history of relapses. There are still too few cases of patients taking DMTs while breastfeeding to be able to provide an encompassing suggestion for all patients, but the data seems promising for use of GA and IFN-β while breastfeeding.