The effect of multiple sclerosis (MS) drugs on fertility is a complex topic because MS treatments vary widely in their mechanisms, potential side effects, and impacts on reproductive health. MS drugs, particularly disease-modifying therapies (DMTs), are designed to alter the immune system to reduce disease activity, but their influence on fertility can differ depending on the specific medication, the patient’s sex, and timing relative to conception or pregnancy.
Many commonly used MS drugs do not appear to directly impair fertility in men or women, but some have important considerations regarding pregnancy and reproductive planning. For women, certain medications can pose risks to a developing fetus or require contraception during and after treatment due to potential teratogenic effects or fetal harm. For men, some treatments may affect sperm quality or reproductive hormones, although this is less commonly reported.
**Disease-Modifying Therapies (DMTs) and Fertility**
DMTs are the cornerstone of MS treatment and include injectable medications like interferon beta and glatiramer acetate, oral agents such as fingolimod (Gilenya) and siponimod (Mayzent), and monoclonal antibodies. Their effects on fertility vary:
– **Interferon beta and Glatiramer Acetate:** These injectable DMTs are generally considered safe regarding fertility. Glatiramer acetate is regarded as safe during pregnancy, and interferon beta may be used with caution. Neither is strongly linked to fertility impairment, but pregnancy planning should still involve medical consultation.
– **Fingolimod (Gilenya):** This oral medication has been associated with fetal harm in animal studies and increased risk of birth defects in humans. Women of reproductive age are advised to use effective contraception during treatment and for at least two months after stopping fingolimod because the drug remains in the body for an extended period. While direct effects on fertility are less clear, the drug’s teratogenic potential means pregnancy must be carefully avoided during treatment.
– **Siponimod (Mayzent):** Similar to fingolimod, siponimod can cause embryotoxicity and fetal abnormalities in animal studies. There is limited human data, but the drug’s mechanism suggests a risk to fetal development. Women should avoid pregnancy during treatment and use contraception.
– **Other Oral Agents and Monoclonal Antibodies:** Some newer oral agents and monoclonal antibodies have limited data on fertility effects. However, many require contraception during treatment due to potential fetal risks. The impact on male fertility is less well studied but generally considered minimal.
**Chemotherapy and Stem Cell Treatments**
In severe MS cases, chemotherapy agents like mitoxantrone or high-dose chemotherapy combined with autologous stem cell transplantation (ASCT) may be used. These treatments can have significant effects on fertility:
– Chemotherapy drugs can damage reproductive cells, leading to temporary or permanent infertility in both men and women. This includes reduced sperm count or quality in men and ovarian reserve depletion in women.
– ASCT involves collecting stem cells, administering high-dose chemotherapy to reset the immune system, and reinfusing the stem cells. While this approach can be effective for MS, the chemotherapy component poses a high risk of fertility loss.
Patients considering these treatments often discuss fertility preservation options, such as sperm banking or egg freezing, before therapy.
**Pregnancy and MS Drugs**
Pregnancy planning is a critical aspect of managing MS in women of reproductive age. Many MS drugs are contraindicated during pregnancy due to risks of miscarriage, low birth weight, or birth defects. Some drugs, like glatiramer acetate, have a better safety profile and may be continued under medical supervision. Others require stopping well before conception to allow drug clearance from the body.
MS itself can increase pregnancy complications, including higher miscarriage rates and low birth weight, so careful coordination between neurologists and obstetricians is essential.
**Male Fertilit
