"Female fertility" refers to a woman's ability to conceive a child and give birth. It refers to how easily a woman can become pregnant and have a healthy pregnancy. Full definition
At a purely biological level, then, the role of the male is to introduce something new into the context of female fertility which enables that fertility to come to fruition. (faith.org.uk)
For me, the best candidate is the dramatic decline in female fertility. (newscientist.com)
For example, a researcher could modify a rat genome to contain a broken version of a gene necessary for female fertility, and introduce some of these rats to an island. (scientificamerican.com)