A couple is considered infertile/sterile if they have been trying to conceive for over 12 months with no luck or in cases of recurrent pregnancy loss (RPL).
In general, it is at that point when you are recommended to see a fertility doctor and undergo all the necessary tests to detect what is causing infertility/sterility. Once done, the specialist will be able to determine what would be the best infertility treatment for you.
When the woman is over 37, this period of time trying to conceive is reduced to 6 months. Third-party assisted reproduction is usually advisable for women aged 40 to 50 or over.