There are no contraindications to breast-feeding unless the mother is taking drugs that are toxic to the infant.⁴ One retrospective study of more than 400 women with MS found no association between postpartum relapse rate and breast-feeding.²⁰ There is even some evidence to suggest that breast-feeding may improve MS status. One study found that subjects who breast-fed had slower progression of MS than did nonnursing mothers.²¹ A more recent study documented no significant differences in rate of relapse between women who breast-fed in the year after pregnancy and those who did not, but when the entire 33-month study period was evaluated, a significantly lower rate in the breast-feeding mothers was observed.⁶

Both patients with MS and their neurologists may be concerned about the need for alterations in treatment during pregnancy and the puerperium. Ordinarily, early initiation of immunomodulator therapy is recommended for relapsing MS.²² In addition, mitoxantrone, an immunosuppressant, is indicated for secondary progressive, progressive relapsing, or worsening relapsing MS.²³ As with all pharmacologic therapies, however, the potential benefit to the mother must be weighed against the potential risk to the fetus.

The (Avonex^®, Betaseron^®, and Rebif^®) are designated by the Food and Drug Administration as Pregnancy Category C, since there is evidence of an abortifacient effect on pregnancy in animals. No well-controlled studies of the use of these agents in pregnant women have been performed.^24-26 Glatiramer acetate (Copaxone^®) is designated as Pregnancy Category B, indicating that available animal studies have not shown a risk to the fetus, but again, there are no adequate studies in pregnant women.²⁷

A case series presented at the annual meeting of the European Neurological Society in 2001 reported that there were no developmental abnormalities in infants of 11 women who elected to remain on a or glatiramer acetate during pregnancy.²⁸ In addition, a recent retrospective review was conducted of 21 trials involving glatiramer acetate and of post-marketing surveillance data.²⁹ [Note: This review was performed by Patricia K. Coyle, MD, the editor-in-chief of this publication.] There were 30 pregnancies with known outcomes in the approximately 2,400 female patients receiving glatiramer acetate in the clinical trials. Of these, 6 had healthy full-term infants, 5 had spontaneous abortions, 18 had elective abortions, and 1 delivered an infant with cleft lip that was believed to have been caused by carbamazepine use. The post-marketing surveillance data showed that of the 215 pregnancies that had occurred while women were taking glatiramer acetate and for which data were available (of a total of 345 pregnancies), 72% resulted in a healthy full-term infant, 21% in spontaneous abortion, 3% in an infant with a congenital anomaly, and 4% in elective abortion. The most common adverse event in both data collections was spontaneous abortion, which occurred at a rate similar to that in an age-adjusted general population. These preliminary data suggest that use of immunomodulator therapy, particularly glatiramer acetate, is not associated with an increase in adverse events during pregnancy. More data are needed to confirm these results, especially as interferons are known to inhibit cell division, which theoretically could be a reason to avoid fetal exposure to them.

There is sufficient evidence to indicate mitoxantrone should be avoided during pregnancy. Mitoxantrone (Novantrone^®) has been assigned a Pregnancy Category of D because of evidence of human fetal risk.²³ Women who are taking mitoxantrone should be warned to avoid becoming pregnant.

Given the abundance of evidence for an increased relapse rate during the postpartum period, patients with MS and their neurologists may consider changes to the treatment regimen during this period. Intravenous immunoglobulin (IVIG) may be useful. A pilot study conducted in 1996 found that IVIG was effective in preventing childbirth-associated relapse in women who had experienced relapses after previous pregnancies.³⁰ Another small study found that IVIG prevented postpartum relapse in the 14 women who received it after delivery.³¹ Finally, a recent European study has found that women treated with IVIG had a relapse rate that was 33% lower than that seen after delivery in the PRIMS study.³²