In the absence of vaccination, rubella is an endemic disease with epidemics every 6 to 9 years. During the 19621965 global rubella pandemic, an estimated 12.5 million rubella cases occurred in the United States, resulting in 2,000 cases of encephalitis, 11,250 therapeutic or spontaneous abortions, 2,100 neonatal deaths, and 20,000 infants born with CRS.[4]
http://www.cdc.gov/vaccines/pubs/surv-manual/chpt15-crs.html#f4
Rubella is extremely dangerous to pregnant women in the first trimester when many do not even know they are pregnant.
Many easily treated diseases had a greater potential for death or other serious consequences years ago.