Birth Rate or fertility rate is the number of births per 1000 of the population. The birth rate is a measure of fertility. The physiological capacity of a woman to conceive and give birth to a child, regardless of whether it is a live birth or a stillbirth, is called fecundity. Lack of fecundity is called infecundity or sterility.
Infertility, on the other hand, refers to the inability of a woman to bear a child and this includes those who cannot give live birth to a live baby. Infertility can be primary or secondary. Primary infertility is also referred to as involuntary childlessness. Secondary infertility can be involuntary. For instance, a woman has had two children and is now unable to have more due to biological or health factors. It is called secondary since it is caused by a second factor after the previous births.