<prompt> In the perspective of the busy life schedule in the modern society, the accepted minimum period of sexual cohabilitation resulting in no offspring for a couple to be declared infeile is :One yearOne and a half - yearTwo yearsThree years  <response>: One year If a couple fails to achieve pregnancy after one year of unprotected and regular inter course, it is an indication to investingate the couple for infeility. Also know : 90 of couples should conceive after 12 months of unprotected sex. Infeility : - Primary : When no previous pregnancies have occurred. - Secondary : When a prior pregnancy although not necessary although not necessary a live bih, has occurred. Fecundability : is the probability of achieving pregnancy within a single menstrual cycle. Fecundity : is the probability of achieving a live bih within a single menstrual cycle. Absolute Infeility : It results from congenital or acquired irreversible loss of functional gametes in either paner or the absence of uterus in females. 