I stopped before I was pregnant. I'm asking now because after I have the baby, I want to start a new drug regiment.
The book "Medications and Mother's Milk" by Dr. Thomas Hale is a good reference for nursing mothers.http://www.amazon.com/Medications-Mothe ... 0984774637
With respect to the two different interferons, Betaseron (Ifn-B1b) and Rebif (Inf-B1a), I would expect that the side effects might be similar. The main difference is that Betaseron is raised in bacteria while Rebif is raised in mammalian cells. This is important since Ifn-B is a normally glycosylated protein (meaning that the body attaches sugar groups to it after the protein is made). Bacteria don't glycosylate proteins. As such, Betaseron is more likely to be seen by the body as a foreign protein and be more antigenic possibly eliciting neutralizing antibodies against the drug. Since both drugs are given by subcutaneous injections, then the injection site reactions might be very similar. You can check with your doctor, but the only way to know if your body responds the same to Rebif as it did to Betaseron may be to give Rebif a short trial run.
I was on Avonex for 10 years so I don't have any experience with either Rebif or Betaseron. However, I did personally know someone on Betaseron and they complained that they would get bad injection site reactions. As Avonex is injected intramuscularly, the worst injection site reactions I typically would get were quarter sized bruises, but these were infrequent. The "flu like" side effects were the main side effect that I struggled with, e.g., chills, fevers, shakes and feeling run down with a near complete lack of energy the day following my injection. However, these lessened after about a year and were fairly manageable with ibuprofen by two or three years.