<P> Female fertility is affected by age . Age is thus a major fertility factor for women . Menarche , the first menstrual period , usually occurs around 12 - 13 , although it may happen earlier or later , depending on each girl . After puberty , female fertility increases and then decreases , with advanced maternal age causing an increased risk of female infertility . In humans , a woman 's fertility peaks in the early and mid-20s , after which it starts to decline slowly . While many sources suggest a more dramatic drop at around 35 , this is unclear since studies are still cited from the nineteenth century and earlier . One 2004 study of European women found fertility of the 27 - 34 and the 35 -- 39 groups had only a four - percent difference . At age 45 , a woman starting to try to conceive will have no live birth in 50 -- 80 percent of cases . Menopause , or the cessation of menstrual periods , generally occurs in the 40s and 50s and marks the cessation of fertility , although age - related infertility can occur before then . The relationship between age and female fertility is sometimes referred to as a woman 's `` biological clock . '' </P>
<P> Female fertility is affected by age . Age is thus a major fertility factor for women . Menarche , the first menstrual period , usually occurs around 12 - 13 , although it may happen earlier or later , depending on each girl . After puberty , female fertility increases and then decreases , with advanced maternal age causing an increased risk of female infertility . In humans , a woman 's fertility peaks in the early and mid-20s , after which it starts to decline slowly . While many sources suggest a more dramatic drop at around 35 , this is unclear since studies are still cited from the nineteenth century and earlier . One 2004 study of European women found fertility of the 27 - 34 and the 35 -- 39 groups had only a four - percent difference . At age 45 , a woman starting to try to conceive will have no live birth in 50 -- 80 percent of cases . Menopause , or the cessation of menstrual periods , generally occurs in the 40s and 50s and marks the cessation of fertility , although age - related infertility can occur before then . The relationship between age and female fertility is sometimes referred to as a woman 's `` biological clock . '' </P>
when does a woman 's biological clock stop
when does a woman 's biological clock stop
Menopause , or the cessation of menstrual periods , generally occurs in the 40s and 50s and marks the cessation of fertility
Menopause , or the cessation of menstrual periods , generally occurs in the 40s and 50s and marks the cessation of fertility