When one decides to have children, one has to decide: how one intends to bring them up, what values one will imbue in them and how one will stress their importance. Whatever they may be, when one instills the right values in a child, one later receives the dividends of one's efforts. This was proved so true this past Yom Kippur for Rebbetzin Judith Friedlander.
I'm not a doctor, nor a biological scientist, but I do know that people under stress produce a hormone called cortisol, which helps the body deal with a stressful event by increasing energy and immunity and even lowering sensitivity to pain.
The mitzvah of taharat hamishpachah (family purity) can be a source of great marital fulfillment and vitality, yet can also - especially for the female partner - cause significant stress, confusion even misery.