The age at which women can conceive children is around the time of menarche (first menstrual period), which can happen anywhere from age 8 to age 16. It seems to be happening earlier and earlier, and many scientists think it has to do with the hormones from birth control medications getting into our water supplies. Unfortunately, water treatment plants aren't able to filter out the residue from the urine and feces sewage treatment facilities deal with all the time.... It's even affecting fish!
what do you mean by "mature"? Women are born with millions of eggs. Only one ripens and matures every month.This is called ovulation. If the egg is not fertilized, the uterine lining sheds causing a menstrual cycle. This happens every month until her ovaries run out of eggs. Thus a woman's reproductive system is mature after the very first ovulation occurs. Does this help?