Very often there are techniques to restore true fertility (the ability to get pregnant via marital intercourse) involving things as seemingly simple as a different diet, wearing boxer shorts rather than jockey shorts (yes, gentlemen, this has a big impact on sperm count), correcting abnormal hormonal levels, or better timing (using NFP to pinpoint the best days for conception.)
Some of this can be founding under the heading of NAPRO-TECHNOLOGY
I wish these things were MUCH better known, because OB/GYN's often go straight to expensive, often unsuccessful artificial reproductive technologies rather than seriously diagnosing and correcting the reason for the infertility.
The Catholic Church prohibits artificial insemination as morally objectionable.
Lots of things, as you pointed out, have an influence on the ability of couples to get pregnant.
In our case, it was purely mechanical. Without getting too graphic or specific, let's just say that the hallway to the palace was longer, more curved and narrower than normal, especially just before the palace entrance.
The tadpole nozzle, OTOH, had plenty of length but was thicker than normal, not fitting far enough down the hallway and, as a result, all the tadpoles were getting out and swimming themselves to death before they got to the palace.
A combination of a pillow to elevate her backside and thereby change the angle of the tadpole nozzle's entrance, a little more patience in putting the nozzle in more slowly and further down and the help of gravity in making sure the tadpoles didn't have to swim so far worked wonders.
The OBGYN explained it was a fairly common problem and fairly easily cured before we even ran any expensive tests. He also explained that, over time, the hallway and nozzle adapted to the unique shapes and sizes of each and made for a better fit-- another argument in favor of marital fidelity!
We were PG within 6 weeks of the visit! The same OBGYN delivered our first two daughters and told us some research indicated that the better swimming tadpoles carried the daughter code. There must be something to it since #3 was also a daughter.
We laugh about it now because it seems so obvious, but it didn't at the time.