My Igm test for rubella has increased from 8.6 to...

regarding your tests :
high IgG positive means you are immune to rubella , although IgM is changing and positive as well , but it does not indicate infection , so you are safe and your pregnancy is safe 
General advices during pregnancy : 
1. See your doctor regularly to check on your health and your pregnancy 
2. Get enough rest
3. exercise regularly
4. avoid smoking and alcohol
5. Avoid taking any medications without consulting the doctor
General advice regarding nutrition during pregnancy?
1. eat healthy foods constantly
2. Eat more vegetables and fruits and avoid fatty and oily food 
3. Avoid fast foods and processed food 
4. Drink enough water