What is the disease-modifying therapy (DMT) of choice for multiple sclerosis (MS) during pregnancy?

Disease-Modifying Therapy for Multiple Sclerosis During Pregnancy

Glatiramer acetate is the disease-modifying therapy of choice for multiple sclerosis during pregnancy due to its established safety profile and lack of teratogenic effects.

Safety Profiles of DMTs During Pregnancy

First-Line Options:

Glatiramer Acetate

• Most favorable safety profile for use during pregnancy
• Multiple studies demonstrate no increased risk of congenital anomalies 1, 2
• Data from the Teva global pharmacovigilance database with over 7,000 pregnancies shows no higher risk for congenital anomalies compared to general population 2
• Pregnancy Category B rating 3
• Can be continued throughout pregnancy in patients with highly active disease 4
• No need to withdraw before conception 4

Interferon Beta

• Generally considered safe but with slightly less robust safety data than glatiramer acetate
• FDA label indicates no drug-associated risk of major birth defects identified in large population-based cohort studies 5
• Some inconsistent findings regarding potential risk for low birth weight or miscarriage 5
• Small cohort studies suggest possible association with decreased mean birth weight and preterm birth, though not confirmed in larger studies 5

DMTs to Avoid During Pregnancy:

• Oral DMTs may be associated with fetal risk 6
• Tyrosine kinase inhibitors are not recommended during pregnancy 7

Management Algorithm for MS During Pregnancy

1. Pre-conception planning:

   • Assess disease activity and severity
   • Plan pregnancy during periods of disease quiescence when possible 8
   • Perform baseline laboratory assessment

2. DMT selection based on disease activity:

   • For patients with mild-moderate MS:

     • Glatiramer acetate is preferred and can be continued throughout pregnancy
     • Alternatively, interferon beta can be used but with slightly more caution

   • For patients with highly active MS:

     • Consider continuing glatiramer acetate throughout pregnancy 4
     • For very active disease, monoclonal antibodies may be given before conception but not during second trimester or later due to risk of neonatal hematological abnormalities 6

3. Monitoring during pregnancy:

   • Laboratory assessment at least once per trimester 8
   • Monitor for disease activity
   • Consider low-dose aspirin (81-100mg daily) if there are risk factors for preeclampsia 8

4. Postpartum management:

   • Encourage breastfeeding as it's associated with decreased risk of postpartum relapses 6
   • Injectable DMTs (glatiramer acetate, interferon beta) likely have low transfer into breastmilk and can be considered during breastfeeding 6
   • Monitor closely for 3-6 months postpartum due to increased risk of disease flare 8

Important Considerations

• Active disease management: Both active MS and continuous high-dose glucocorticoid treatment have potential for maternal and fetal harm, so maintaining disease control with pregnancy-compatible medications is crucial 7

• Breastfeeding: Women should be encouraged to breastfeed as it may reduce postpartum relapse risk 6

• Common pitfalls to avoid:

  1. Discontinuing all DMTs before conception without a plan for disease control
  2. Failing to recognize that untreated active disease poses risks to both mother and fetus
  3. Not planning for postpartum disease management when relapse risk increases

The evidence strongly supports glatiramer acetate as the safest DMT option during pregnancy for women with MS, with interferon beta as an alternative with slightly less robust safety data. The decision should prioritize maintaining disease control while minimizing fetal risk.