Most jobs require a training period to acquaint you with new job responsibilities. But for the job of parenting, little education is available. Parental uncertainty doesn't necessarily disappear as children grow. Just as we learn what to expect of an infant, the child becomes a toddler. Parental stress may increase if parents are unable to change their expectations and demands as children grow.
Children change the most rapidly during the first two years of life and as they reach adolescence.
Therefore parents may experience high levels of stress during these time periods unless they learn to adjust to a changing child. It takes time, patience, experience, and effort to build a positive parent-child relationship and become an effective parent. In addition to feeling inadequate about how to parent, mothers and fathers may sometimes be bothered by feelings of resentment. No one ever told you it would be like this. Taking care of children demands so much time and energy that it's not always possible to do some of the other things that are important to you.