Smaller families tend to result in higher IQ, academic achievement, and occupational performance. Large families produce more delinquents and alcoholics. Perinatal morbidity and mortality rates are higher in large families as birth weights decrease.
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 do children of larger families.
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.
Meanwhile some effects of small family size are:

1. It may bring about the under-utilization of economic resources.
2. A small family size may not be able to have more people that will vote during election.
3. Small family size will produce inadequate labour force which will be smaller than that of a larger family.
4. It brings about low output because of its small nature.
5. It will have wastage of output. In case the family produces more than it can consume, it will be wasted or given out to those that do not labour with them. This is because the family is small.