They are two very different concepts.
Sterility is the inability to conceive whereas infertility is the inability to carry a pregnancy to term with the birth of a healthy child.
The difference is not just conceptual as the studies which aim to understand the causes, treatments and solutions are completely different.
It is not the same treating a couple who can not conceive as a couple who conceive regularly without difficulty but who sadly can not develop an evolutive pregnancy.
After a year of sexual intercourse without contraception and no pregnancy has been achieved. This waiting period is shortened for women aged between 35 and 40 years of age and there should be no waiting period for women over 40. In addition, if one of the members of the couple have a gynaecological or an andrological history, a fertility study should be completed without delay.
Although traditionally we referred to infertility when there were three or more miscarriages, due to the great emotional pain involved in losing a wanted pregnancy, currently we recommend a fertility study after just two miscarriages.
As in the case of sterility if there is a history of problems related to reproduction, the couple should not wait to seek medical help.
We speak of primary sterility if the couple has never conceived and secondary sterility when the problem occurs subsequent to achieving one prior pregnancy.
We speak of primary infertility when no pregnancy has been carried to term and secondary infertility if there is repeated miscarriage after one full term pregnancy.