Most females are capable of conceiving and bearing children beginning in their mid-teen years.
While women in industrialized societies usually bear children in their 20s and 30s, women can give birth well into their 40s and beyond. Men can be fertile into extreme old age. But the process of reproduction is immensely complex. For conception to take place and pregnancy to begin, hundreds of individual hormonal, chemical, and physical events must take place in a precise order. In the tube, it must encounter a viable egg within 12 hours or so of its monthly release, attach itself to the egg, penetrate its outer vestments and fertilize the ovum within.