The society says some women may be waiting too long to start their families, perhaps because they over-estimate their chances of successfully conceiving with fertility treatments, if the need arises.
It says women in their 20s and 30s need better reproductive counselling so that they have an accurate grasp of what waiting to start their families does to their chances of conceiving.
It says women need to know that fertility begins to decline significantly in the early- to mid-30s and that male fertility also declines with age.
"Some Canadian women may be inadvertently postponing pregnancy too long," says Dr. Kimberly Liu, principal co-author of the new guideline.
"There is a sense that women may be over-estimating the potential of assisted human reproductive technologies and underestimating the risks and complications associated with delaying pregnancy.”
A statement from the society says a lot of women are unaware of the limitations of assisted reproduction, as well as the fact that the success rates of these options decline steadily as women hit their late 30s and 40s.
"Fertility treatments aren’t a sure-fire route to pregnancy -- their rates of success are greatly influenced by age-related declines in fertility," says Dr. Allison Case, Liu's co-author of the guideline.
"Time can be of the essence for a woman in her thirties who needs assistive reproductive technology -- it is important that she gets appropriate treatment for her age."
The society says the proportion of women who delay childbearing beyond the age of 35 has increased significantly in recent decades.