The older you get the higher the chance you have of risking complications during pregnancy or having the baby be born with birth defects so it's really not a good idea to try to have a baby once your turn 50 years old.
Although The oldest verified mother to conceive a baby naturally (listed currently as of January 26th 2017 in the Guinness Records) is Dawn Brooke (UK); she conceived a son at the age of 59 years old in the year of 1997.
Really once you get to 30 years old or above the risk of complications with childbirth and birth defects increase but you can still try if you really want to try having a baby.