What is the latest age to get fertility?

There is none: There is no age cut off for fertility. As long as you ovulate, you can get pregnant. Now, if you mean safe pregnancy (less chance of birth defects), the older you are, the higher the risk. Anytime >30, the risk starts rising faster.

Fertility & age: Men can reproduce till their 70's, but the risk of abnormalities increases due to abnormalities in sperm dna (i can't imagine having kids at that age, but some may want to). Women, unfortunately have increased chromosomal issues after 35, and around 42 +/- menopause begins. So it's reasonable to start having kids earlier than 35.

Also : As a general rule though pregnancy after 45 is extremely rare. Most infertility doctors strongly discourage fertility treatment after age 43-44. If you are over age 35 and you have tried to conceive without success then seek immediate help. If you are > 44 talk to your doctor about alternative methods to start a family. Adoption or donor eggs are good options.