Separation protest (also called separation anxiety) usually starts around 6 months of age, peaks near 10 months of age, and starts to fade sometime near the first birthday. Some children's separation protests may peak at or continue through to about 18 months of age, resolving closer to the second birthday. The intensity and duration of separation protest is affected by your child's temperament as well as your personality and how you respond.
Here are some suggestions on how to deal, as well as possible, with these scenes:
WebMD Medical Reference from Healthwise