Hi.. I agree with others posters that moms tend to vary on this.. However, my daughter was on breastmilk exclusively for 5 months. then it was breast milk and solids till 12 months when I shifted to regular cow's milk. It was easy for me since I was a SAHM plus my daughter gained weight beautfully and even, her immunity is quite good.. **Touchwood**
However, I do feel strongly about breastfeeding at least for the first 6 months and then, deciding to start formula. I guess, it depends on the mom and baby eventually,though.