“Levels of ‘viable’ sperm in human males are falling – and scientists believe they now understand the cause. Infertility can begin in the womb, says Steve Connor”
The current consensus is that the number of Sertoli cells formed during fetal development determines the number of sperm produced in the adult male.
Maternal health determines a number of health matters for the children. I believe this is an important concept to remember because lay people and medical professionals often attribute side effects and complications to present conditions but, at least in some cases, the problem started in the womb.