You decide. Ovarian reserves may determine this for you, fertility naturally declines with age. Then what risks are you willing to deal with? Downs syndrome increases logarithmically, as do other genetic abnormalities. Eg. Age 45, 1/9 chance. Misscarriage increases with age as well. How is your overall health? Risks of diabetes and hypertension go up. Are you willling to have an amniocentesis or cvs?