Smaller families tend to result in higher IQ, academic achievement, and occupational performance. 
Each child receives more parental attention and educational advantages, which generally raise her self-esteem. Children in small families, especially first and only children, tend to have higher school and personal achievement levels than the children of larger families.
If you have just one or two children, you may become overprotective and overly attentive. This may make your child reluctant to be separated from you, hindering the development of new relationships with peers. In fact, you may have that same difficulty. Small family size will produce inadequate labour force which will be smaller than that of a larger family. It brings about low output because of its small nature. It will have wastage of output.