Abstract
The two main ways in which disease and nutrition can influence fertility are by reducing fecundity or by extending the birth interval. Fecundity refers to reproductive ability, that is the potential to breed, as compared to fertility which denotes actual childbearing . Reduced fecundity, which is usually referred to as subfecundity, results from impairment of any of the biological aspects of reproduction, including coital inability, conceptive failure as well as pregnancy loss. Subfecundity is only one factor operating to reduce fertility; other factors include those governing mate exposure and birth control