In the perspective of the busy life schedule in the modern society, the accepted minimum period of sexual co-habitation resulting in no offspring for a couple to be declared as infeile is:

Infeility is defined as a failure to conceive within one year of regular unprotected coitus. Primary Infeilty denotes those patients who have never conceived. Seconday Infeility indicates previous pregnancy but failure to conceive subsequently. Reference- DC Dutta's Textbook of gynaecology 7th edition page no.186