Newborn babies sleep a lot, usually waking up every 2 to 4 hours for feedings. At about 2-3 months of age, they generally start sleeping through the night; although a few cooperative babies may start sooner. Starting solid foods does not usually make a baby sleep through the night.
Between 5 and 7 months of age, your baby may disappoint you by starting to wake once again during the night. This isn’t backsliding. It’s a normal developmental phase. Let her stay in her bed, comfort her, pat her on the back, and change her if needed. The pattern of nighttime sleeping will soon return. Try not to nurse your infant or use a bottle to put them back to sleep at this age.