And the list goes on....
As you can see, conceving a baby is a detailed process. It all has to line up for conception to be successful and for baby to be born healthy. Here is what also has to happen:
*The fallopian tube needs to transport the 3 day old embryo down to the uterus
*The embryo must become a blastocyst
*The blastocyst must break out of its shell
*The endometrial lining of the uterus must be healthy and receptive to the embryo
*After breaking out of its shell, the blastocyst must attach to the endometrium and implant
These are just a few events out of hundreds of biochemical and molecular events that have to go off without a hitch in order for pregnancy to occur.
Standard tests for infertility can't begin to come close to testing for each and every complex step that can go wrong. The tests only look for the most obvious factors for infertility, for instance abnormal sperm counts, ovulatory problems, and blocked fallopian tubes.
None of the tests as yet address the molecular issues. One can only look to the future for the broadening of scientific knowledge regarding infertility causes and treatments.