Image source: Cleveland Clinic Fertility is the natural capability to produce offspring. As a measure, fertility rate is the number of offspring born per mating pair, individual or population. Fertility differs from fecundity , which is defined as the potential for reproduction (influenced by gamete production, fertilization and carrying a pregnancy to term) [1] A lack of fertility is infertility while a lack of fecundity would be called sterility . Human fertility depends on factors of nutrition , sexual behavior , consanguinity , culture , instinct , endocrinology , timing, economics , way of life, and emotions . Adapted from Wikipedia