A woman can really get pregnant at any age however a woman is usually the most fertile in before the woman turns 20 and during their 20's.
They say after 40 years of age the chance of complications during pregnancy are higher but my mom had me when she was 44 years of age and had no complications and I've known a 60 year old woman who got pregnant with her first ever child.
So if possible you should try having kids before you turn 40 but there still is a chance that you may get pregnant later on in life even during your 60's.